Park locking mechanism for an automatic transmission

ABSTRACT

A park locking mechanism for a four-speed automatic transmission in which the rollers have oversized bores to reduce the reaction loads transmitted to the carrier pins so as to increase the service life of the carrier pins and rollers.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The present invention relates to an automatic transmission primarilyintended for motor vehicle use, and more particularly, to a doubleroller parking sprag locking mechanism for an automatic transmission.

2. Description Of Related Art

Generally speaking, land vehicles require three basic components. Thesecomponents comprise a power plant (such as an internal combustionengine) a power train and wheels. The internal combustion engineproduces force by the conversion of the chemical energy in a liquid fuelinto the mechanical energy of motion (kinetic energy). The function ofthe power train is to transmit this resultant force to the wheels toprovide movement of the vehicle.

The power train's main component is typically referred to as the"transmission". Engine torque and speed are converted in thetransmission in accordance with the tractive-power demand of thevehicle. The vehicle's transmission is also capable of controlling thedirection of rotation being applied to the wheels, so that the vehiclemay be driven both forward and backward.

A conventional transmission includes a hydrodynamic torque converter totransfer engine torque from the engine crankshaft to a rotatable inputmember of the transmission through fluid-flow forces. The transmissionalso includes frictional units which couple the rotating input member toone or more members of a planetary gearset. Other frictional units,typically referred to as brakes, hold members of the planetary gearsetstationary during flow of power. These frictional units are usuallybrake clutch assemblies or band brakes. The drive clutch assemblies cancouple the rotating input member of the transmission to the desiredelements of the planetary gearsets, while the brakes hold elements ofthese gearsets stationary. Such transmission systems also typicallyprovide for one or more planetary gearsets in order to provide variousratios of torque and to ensure that the available torque and therespective tractive power demand are matched to each other.

Transmissions are generally referred to as manually actuated orautomatic transmissions. Manual transmissions generally includemechanical mechanisms for coupling rotating gears to produce differentratio outputs to the drive wheels.

Automatic transmissions are designed to take automatic control of thefrictional units, gear ratio selection and gear shifting. A thoroughdescription of general automatic transmission design principals may befound in "Fundamentals of Automatic Transmissions and Transaxles,"Chrysler Corporation Training Manual No. TM-508A. Additionaldescriptions of automatic transmissions may be found in U.S. Pat. No.3,631,744, entitled "Hydromatic Transmission," issued January 4, 1972 toBlomquist, et al., and U.S. Pat. No. 4,289,048, entitled "Lock-up Systemfor Torque Converter," issued on September 15, 1981 to Mikel, et al.Each of these patents is hereby incorporated by reference.

In general, the major components features in such an automatictransmission are: a torque converter as above-mentioned; fluidpressure-operated multi-plate drive or brake clutches and/or brake bandswhich are connected to the individual elements of the planetary gearsetsin order to perform gear shifts without interrupting the tractive power;one-way clutches in conjunction with the frictional units foroptimization of power shifts; and transmission controls such as valvesfor applying and releasing elements to shift the gears (instant ofshifting), for enabling power shifting, and for choosing the proper gear(shift point control), dependent on shift-program selection by thedriver (selector lever), accelerator position, the engine condition andvehicle speed.

The control system of the automatic transmission is typicallyhydraulically operated through the use of several valves to direct andregulate the supply of pressure. This hydraulic pressure control willcause either the actuation or deactuation of the respective frictionalunits for effecting gear changes in the transmission. The valves used inthe hydraulic control circuit typically comprise spring-biased spoolvalves, spring-biased accumulators and ball check valves. Since many ofthese valves rely upon springs to provide a predetermined amount offorce, it will be appreciated that each transmission design represents afinely tuned arrangement of interdependent valve components. While thistype of transmission control system has worked well over the years, itdoes have its limitations. For example, such hydraulically controlledtransmissions are generally limited to one or a very small number ofengines and vehicle designs. Therefore, considerable cost is incurred byan automobile manufacturer to design, test, build, inventory and repairseveral different transmission units in order to provide an acceptablebroad model line for consumers.

Additionally, it should be appreciated that such hydraulicallycontrolled transmission systems cannot readily adjust themselves in thefield to compensate for varying conditions such as normal wear oncomponents, temperature swings and changes in engine performance overtime. While each transmission is designed to operate most efficientlywithin certain specific tolerances, typical hydraulic control systemsare incapable of taking self corrective action on their own to maintainoperation of the transmission at peak efficiency.

However, in recent years, a more advanced form of transmission controlsystem has been proposed, which would offer the possibility of enablingthe transmission to adapt itself to changing conditions. In this regard,U.S. Pat. No. 3,956,947, issued on May 18, 1976 to Leising, et al.,which is hereby incorporated by reference, sets forth a fundamentaldevelopment in this field. Specifically, this patent discloses anautomatic transmission design which features an "adaptive" controlsystem that includes electrically operated solenoid-actuated valves forcontrolling certain fluid pressures. In accordance with thiselectric/hydraulic control system, the automatic transmission would be"responsive" to an acceleration factor for controlling the output torqueof the transmission during a shift from one ratio of rotation (betweenthe input and output shafts of the transmission) to another.Specifically, the operation of the solenoid-actuated valves would causea rotational speed versus time curve of a sensed rotational component ofthe transmission to substantially follow along a predetermined pathduring shifting.

3. Objects Of The Present Invention

It is one object of the present invention to provide a four-speedautomatic transmission design which can be readily utilized inconjunction with a variety of engines and vehicle sizes and types,including vehicles presently using conventional, mechanical-hydraulicautomatic transmission systems.

It is an additional object of the present invention to eliminate theneed for a few certain elements (clutches, bands, one-way clutches)which are normally required to provide acceptable shift quality.

It is a more specific object of the present invention to provide alow-effort double roller parking sprag locking mechanism for anautomatic transmission to increase the service life of the park lockingmechanism.

This application is one of several applications filed on the same date,all commonly assigned and having similar Specification and Drawings,these applications being identified below:

    ______________________________________                                        U.S. Ser.                                                                     No.    Title                                                                  ______________________________________                                        187,772                                                                              AN ELECTRONICALLY-CONTROLLED,                                                 ADAPTIVE AUTOMATIC TRANSMISSION                                               SYSTEM                                                                 187,751                                                                              AUTOMATIC FOUR-SPEED TRANSMISSION                                      189,493                                                                              PUSH/PULL CLUTCH APPLY PISTON OF AN                                           AUTOMATIC TRANSMISSION                                                 187,781                                                                              SHARED REACTION PLATES BETWEEN                                                CLUTCH ASSEMBLIES IN AN AUTOMATIC                                             TRANSMISSION                                                           189,492                                                                              CLUTCH REACTION AND PRESSURE PLATES                                           IN AN AUTOMATIC TRANSMISSION                                           188,602                                                                              BLEEDER BALL CHECK VALVES IN AN                                               AUTOMATIC TRANSMISSION                                                 188,610                                                                              PRESSURE BALANCED PISTONS IN AN                                               AUTOMATIC TRANSMISSION                                                 189,494                                                                              DOUBLE-ACTING SPRING IN AN                                                    AUTOMATIC TRANSMISSION                                                 187,770                                                                              SOLENOID-ACTUATED VALVE                                                       ARRANGEMENT OF AN AUTOMATIC                                                   TRANSMISSION SYSTEM                                                    187,796                                                                              RECIPROCATING VALVES IN A FLUID                                               SYSTEM OF AN AUTOMATIC TRANSMISSION                                    187,705                                                                              VENT RESERVOIR IN A FLUID SYSTEM OF                                           AN AUTOMATIC TRANSMISSION                                              188,592                                                                              FLUID ACTUATED SWITCH VALVE IN AN                                             AUTOMATIC TRANSMISSION                                                 188,598                                                                              DIRECT-ACTING, NON-CLOSE CLEARANCE                                            SOLENOID-ACTUATED VALVES                                               188,618                                                                              NOISE CONTROL DEVICE FOR A                                                    SOLENOID-ACTUATED VALVE                                                188,605                                                                              FLUID ACTUATED PRESSURE SWITCH FOR                                            AN AUTOMATIC TRANSMISSION                                              187,210                                                                              METHOD OF APPLYING REVERSE GEAR OF                                            AN AUTOMATIC TRANSMISSION                                              187,672                                                                              TORQUE CONVERTER CONTROL VALVE IN A                                           FLUID SYSTEM OF AN AUTOMATIC                                                  TRANSMISSION                                                           187,120                                                                              CAM-CONTROLLED MANUAL VALVE IN AN                                             AUTOMATIC TRANSMISSION                                                 187,181                                                                              FLUID SWITCHING MANUALLY BETWEEN                                              VALVES IN AN AUTOMATIC TRANSMISSION                                    187,704                                                                              METHOD OF OPERATING AN ELECTRONIC                                             AUTOMATIC TRANSMISSION SYSTEM                                          188,020                                                                              METHOD OF SHIFT SELECTION IN AN                                               ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 187,991                                                                              METHOD OF UNIVERSALLY ORGANIZING                                              SHIFTS FOR AN ELECTRONIC AUTOMATIC                                            TRANSMISSION SYSTEM                                                    188,603                                                                              METHOD OF DETERMINING AND                                                     CONTROLLING THE LOCK-UP OF A TORQUE                                           CONVERTER IN AN ELECTRONIC                                                    AUTOMATIC TRANSMISSION SYSTEM                                          188,617                                                                              METHOD OF ADAPTIVELY IDLING AN                                                ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 189,553                                                                              METHOD OF DETERMINING THE DRIVER                                              SELECTED OPERATING MODE OF AN                                                 AUTOMATIC TRANSMISSION SYSTEM                                          188,615                                                                              METHOD OF DETERMINING THE SHIFT                                               LEVER POSITION OF AN ELECTRONIC                                               AUTOMATIC TRANSMISSION SYSTEM                                          188,837                                                                              METHOD OF DETERMINING THE                                                     ACCELERATION OF A TURBINE IN AN                                               AUTOMATIC TRANSMISSION                                                 187,771                                                                              METHOD OF DETERMINING THE FLUID                                               TEMPERATURE OF AN ELECTRONIC                                                  AUTOMATIC TRANSMISSION SYSTEM                                          188,607                                                                              METHOD OF DETERMINING THE                                                     CONTINUITY OF SOLENOIDS IN AN                                                 ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 189,579                                                                              METHOD OF DETERMINING THE THROTTLE                                            ANGLE POSITION FOR AN ELECTRONIC                                              AUTOMATIC TRANSMISSION SYSTEM                                          189,604                                                                              METHOD OF CONTROLLING THE SPEED                                               CHANGE OF A KICKDOWN SHIFT FOR AN                                             ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 188,591                                                                              METHOD OF CONTROLLING THE APPLY                                               ELEMENT DURING A KICKDOWN SHIFT FOR                                           ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 188,608                                                                              METHOD OF CALCULATING TORQUE FOR AN                                           ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                                 187,150                                                                              METHOD OF LEARNING FOR ADAPTIVELY                                             CONTROLLING AN ELECTRONIC                                                     AUTOMATIC TRANSMISSION SYSTEM                                          188,595                                                                              METHOD OF ACCUMULATOR CONTROL                                                 FOR A FRICTION ELEMENT IN AN                                                  ELECTRONIC AUTOMATIC                                                          TRANSMISSION SYSTEM                                                    188,599                                                                              METHOD OF ADAPTIVELY SCHEDULING A                                             SHIFT FOR AN ELECTRONIC AUTOMATIC                                             TRANSMISSION SYSTEM                                                    188,601                                                                              METHOD OF SHIFT CONTROL DURING A                                              COASTDOWN SHIFT FOR AN ELECTRONIC                                             AUTOMATIC TRANSMISSION SYSTEM                                          188,620                                                                              METHOD OF TORQUE PHASE SHIFT                                                  CONTROL FOR AN ELECTRONIC AUTOMATIC                                           TRANSMISSION                                                           188,596                                                                              METHOD OF DIAGNOSTIC PROTECTION                                               FOR AN ELECTRONIC AUTOMATIC                                                   TRANSMISSION SYSTEM                                                    188,597                                                                              METHOD OF STALL TORQUE MANAGEMENT                                             FOR AN ELECTRONIC AUTOMATIC                                                   TRANSMISSION SYSTEM                                                    188,606                                                                              METHOD OF SHIFT TORQUE MANAGEMENT                                             FOR AN ELECTRONIC AUTOMATIC                                                   TRANSMISSION SYSTEM                                                    188,616                                                                              ELECTRONIC CONTROLLER FOR AN                                                  AUTOMATIC TRANSMISSION                                                 188,600                                                                              DUAL REGULATOR FOR REDUCING SYSTEM                                            CURRENT DURING AT LEAST ONE MODE OF                                           OPERATION                                                              188,619                                                                              UTILIZATION OF A RESET OUTPUT OF A                                            REGULATOR AS A SYSTEM LOW-VOLTAGE                                             INHIBIT                                                                188,593                                                                              THE USE OF DIODES IN AN INPUT                                                 CIRCUIT TO TAKE ADVANTAGE OF AN                                               ACTIVE PULL-DOWN NETWORK PROVIDED                                             IN A DUAL REGULATOR                                                    188,669                                                                              SHUTDOWN RELAY DRIVER CIRCUIT                                          188,614                                                                              CIRCUIT FOR DETERMINING THE CRANK                                             POSITION OF AN IGNITION SWITCH BY                                             SENSING THE VOLTAGE ACROSS THE                                                STARTER RELAY CONTROL AND HOLDING                                             AN ELECTRONIC DEVICE IN A RESET                                               CONDITION IN RESPONSE THERETO                                          188,612                                                                              THROTTLE POSITION SENSOR DATA                                                 SHARED BETWEEN CONTROLLER WITH                                                DISSIMILAR GROUNDS                                                     188,611                                                                              NEUTRAL START SWITCH TO SENSE SHIFT                                           LEVER POSITION                                                         188,981                                                                              OPEN LOOP CONTROL OF SOLENOID COIL                                            DRIVER                                                                 ______________________________________                                    

SUMMARY OF THE INVENTION

To achieve the foregoing objects, the present invention provides acomprehensive four-speed automatic transmission system. While thistransmission system particularly features a fully adaptive electroniccontrol system, numerous other important advances are incorporated intothis unique transmission system, as will be described below in detail.

In addition to the advantages offered by the adaptive control system,the present invention achieves the combination of this control systemwith a unique four-speed transaxle structure which requires fewercomponents and is smaller than previous four-speed transmission system.For example, the four-speed transmission system according to the presentinvention is capable of fitting into the space made available for aconventional three-speed transmission system.

Additionally, the four-speed transmission system features a low-effortdouble-roller parking sprag locking mechanism for an automatictransmission in which the rollers have oversized bores to reduce thereaction loads transmitted to the carrier pins so as to increase theservice life of the carrier pins and rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome more fully apparent from the following detailed description ofthe preferred embodiment, the appended claims and in the accompanyingdrawings in which:

FIGS. 1A-E illustrate one physical embodiment of the transmissionaccording to the present invention; FIG. 1A is a perspective view,partially broken away of the transmission; FIG. 1B is a sectionalelevational view of one embodiment of a transmission constructedaccording to the present invention; FIG. 1C is a partial sectionalelevational view of one half of the transmission of FIG. 1B; FIG. 1D isa partial sectional elevational view of the other half of thetransmission of FIG. 1B; and FIG. 1E is a schematic diagram of thetransmission of FIGS. 1A and 1B;

FIGS. 2A and 2B illustrate two views of a bleeder ball check valveassembly according to the present invention; FIG. 2A is a frontelevational view of the reaction shaft support and bleeder ball checkvalve assembly; and FIG. 2B is a sectional view of FIG. 2A;

FIGS. 3A-E illustrate the structure and operation of the double actingspring; FIG. 3A is an elevational view of the structure of the doubleacting spring; FIG. 3B is a sectional view taken along lines B--B ofFIG. 3A; FIGS. 3C is a partial sectional elevational view of the springin its non-applied position; FIG. 3D is a partial sectional elevationalview of the spring while the overdrive clutch is being applied; and FIG.3E is a partial sectional elevational view of the spring while thereverse clutch is being applied;

FIGS. 4A-J illustrate the park locking mechanism according to thepresent invention; FIG. 4A is an elevational view, partly in sectionwith parts broken away, of the underside of an automatic transmissionhousing showing the manual lever rotated to its park lock position; FIG.4B is a sectional view taken substantially along line B--B of FIG. 4A;FIG. 4C is a fragmentary view of the park lock mechanism of FIG. 4Bshowing the mechanism in its unlocked mode; FIG. 4D is a fragmentaryview of the park lock mechanism of FIG. 4B showing the mechanism in itslocked mode with the pawl out of registry with a space between adjacentteeth of the parking gear; FIG. 4E is an exploded perspective view ofthe park lock mechanism; FIG. 4F is an enlarged fragmentary sectionalview of the park lock cam rollers; FIG. 4G is a sectional view takensubstantially along line G--G of FIG. 4F; FIG. 4H is a fragmentaryelevational view of the upper surface of the manual lever rotated to itsinstallation position; FIG. 4I is an end elevational fragmentary view ofthe manual lever as viewed in the direction of the arrow of FIG. 3H; andFIG. 4J is a fragmentary perspective view illustrating, in a schematicmanner, the interlocking relationship between the park lock carrier andthe transmission case;

FIGS. 5A-L are schematic diagrams of the hydraulic circuits employed inthe transmission according to the present invention in various gearpositions;

FIG. 6 is a partial exploded view of the valve body and other valvescontained therein of FIGS. 5A-L according to the present invention;

FIG. 7 is a plan view of the solenoid valve manifold assembly with thecover partially broken away of the valves shown in FIGS. 5A-L;

FIG. 8 is a cross-sectional view of the normally ventedsolenoid-actuated valve 632 taken along line 8--8 of FIG. 7;

FIG. 9 is a cross-sectional view of the normally appliedsolenoid-actuated valve 630 taken along line 9--9 of FIG. 7;

FIG. 9A is a partial sectional view of the valve of FIG. 9 with a noisereducing device;

FIG. 10 is a cross-sectional view of a pressure switch of FIGS. 5A-Ltaken along line 10--10 of FIG. 7;

FIG. 11A is a sectional view of the solenoid switch valve of FIGS. 5A-Ltaken along line A--A of FIG. 5; and FIG. 11B is a sectional view of themanual valve of FIGS. 5A-L taken along line B--B of FIG. 5;

FIG. 12 is a flow chart of the overall operational methodology of thetransmission controller according to the present invention;

FIGS. 13A-13C are flow charts of the shift select methodology of FIG. 12according to the present invention;

FIGS. 14A-D illustrate the shift schedule methodology according to thepresent invention; FIG. 14A is a flow chart of the shift schedulemethodology of FIG. 12; and FIGS. 14B-14D are shift schedule graphs;

FIGS. 15A-B illustrate the PSLOPE methodology according to the presentinvention; FIG. 15A is a flow chart of the PSLOPE methodology of FIGS.14; and FIG. 15B is a graph of the method used in FIG. 15A;

FIGS. 16A-D are flow charts of the shift methodology of FIG. 12according to the present invention; FIG. 16A is a flow chart of theupshift methodology; FIGS. 16B and 16C are flow charts of the downshiftmethodology; and FIG. 16D is a flow chart of the garage shiftmethodology;

FIG. 17 is a flow chart of the lock-up methodology of FIG. 12 accordingto the present invention;

FIGS. 18A-C illustrate the adaptive idle methodology according to thepresent invention; FIG. 18A is a flow chart of the adaptive idlemethodology; FIG. 18B is a graph of the cycle time of onesolenoid-actuated valve; and FIG. 18C is a graph of speed versus timefor the turbine of the torque converter;

FIG. 19 is a schematic diagram of the PRNODDL methodology of FIG. 12according to the present invention;

FIGS. 20A and 20B are flow charts of the shift lever positionmethodology according to the present invention;

FIGS. 21A-D illustrate the transmission temperature determinationmethodology according to the present invention; FIGS. 21A and 21C areflow charts of the pressure switch test and transmission temperaturemethodology; FIG. 21D is a graph of a predicted transmission temperaturemethodology;

FIGS. 22A-E illustrate the solenoid continuity test methodologyaccording to the present invention; FIGS. 22A-D are flow charts of thesolenoid continuity test methodology; and FIG. 22E is a graph ofsolenoid driver logic;

FIGS. 23A-C illustrate the throttle angle computation methodologyaccording to the present invention; FIGS. 23A and 23B are flow charts ofthe throttle angle computation methodology; and FIG. 23C is a plot ofvariables used for the throttle angle computation methodology;

FIGS. 24A-L illustrate the shift methodology according to the presentinvention; FIG. 24A is a shift graph tape for a third to first gearkickdown shift; FIG. 24B is a graph of torque converter characteristicsfor the turbine torque methodology; FIG. 24C is a partial shift tapegraph of the learn methodology for kickdown shifts; FIG. 24D is a shifttape graph for a first to second gear upshift; FIG. 24E is a flow chartof the learn methodology; FIG. 24F is a graph for the adaptivescheduling methodology for a fourth to third gear coastdown shift; FIG.24G is a phase plane graph for a second to first gear coastdown shift;FIG. 24H is a partial shift tape graph for a second to first gearcoastdown shift; FIG. 24I is a flow chart of the release element logicfor a kickdown or coastdown shift; FIG. 24J is a flow chart of the applyelement logic for a kickdown or coastdown shift; FIG. 24K is a graph ofpressure versus time for an element; and FIG. 24L is a shift tape graphfor a neutral to reverse gear garage shift;

FIGS. 25A-K are flow charts of the on-board diagnostics according to thepresent invention;

FIGS. 26A-H illustrates the engine torque management methodologyaccording to the present invention; FIGS. 26A-D are flow charts of theengine torque management methodology; and FIGS. 26E-H are shift tapegraphs with and without engine torque management;

FIG. 27A is a block diagram of an adaptive control system for anautomatic transmission according to the present invention;

FIG. 27B is a block diagram of the transmission controller for theadaptive control system according to the present invention;

FIGS. 28A-I comprise a schematic diagram of the transmission controllershown in FIG. 27B; specifically, FIG. 28A illustrates a communicationcircuit which provides a serial communication link between thetransmission controller and the engine controller; FIG. 28B illustratesthe microprocessor and peripheral interface circuits; FIG. 28Cillustrates the read only memory and watchdog/reset circuits; FIG. 28Dillustrates the speed and throttle input circuits; FIG. 28E illustratesthe ignition switch input circuits; FIG. 28F illustrates the regulatorand relay driver circuits; FIG. 28G illustrates the solenoid drivercircuits; FIG. 28H illustrates the pressure switch input and test modecircuits; and FIG. 28I illustrates two additional communication circuitsfor the transmission controller;

FIG. 29 is a block diagram of the interface chip shown in FIG. 28B;

FIG. 30 is a block/schematic diagram of the watchdog/reset chip shown inFIG. 28C,

FIG. 31 is an equivalent circuit schematic diagram illustrating howdiodes can be used in an input circuit to take advantage of an activepull-down network in a switched voltage section of a dual regulator toprovide high voltage protection to a microcomputer with an electrostaticdischarge protection circuit;

FIG. 32 is an equivalent circuit schematic diagram illustrating how areset output of a voltage regulator can be used as a system low voltageinhibit;

FIG. 33 is a diagrammatic drawing showing how the output of a throttleposition sensor can be shared between two electronic controllers havingdissimilar ground potentials;

FIG. 34 is a diagrammatic illustration of a circuit for determining thecrank position of an ignition switch by sensing the voltage across thestarter relay coil and holding an electronic device in a reset conditionin response thereto; and

FIG. 35 is an illustration of closed loop and open loop control ofsolenoid coil drivers showing basic differences between the circuits andbasic similarities between the voltage outputs.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1A and 1B, an automatic transmission 100 according toone embodiment of the present invention is shown. The transmission 100is adapted to be used in a vehicle (not shown), such as an automobile.However, it should be appreciated that the principles of the presentinvention may be employed in other types of vehicles and devices. Thetransmission 100 includes a transmission housing or case 102 forenclosing the numerous subassemblies which make up the transmission 100,including a torque converter assembly 110, pump assembly 200,multi-clutch assembly 300 and gear assembly 500.

TORQUE CONVERTER ASSEMBLY STRUCTURE

The torque converter assembly 110 is operative to transmit power from arotating crankshaft 114 of a prime mover such as an automobile engine(not shown) to the input member of the transmission 100. This power maythen be subsequently transmitted to a drive unit 104 (partially shown)which is connected to one or more drive wheels (not shown) of thevehicle. The torque converter 110 is generally comprised of an impellerassembly 126, turbine assembly 128 and a stator assembly 130.

As illustrated in FIG. 1C, power is transmitted from the rotatingcrankshaft 114 of the engine to a front cover member 116 of the impellerassembly 126 through a rotatable plate member 118. Balance weights 119are circumferentially spaced about the outer periphery of the frontcover member 116. The plate member 118 is secured proximate its innerperiphery to the crankshaft 114 by suitable fastening means such asbolts 120, and is likewise secured proximate its outer periphery to thefront cover member 116 by suitable fastening means such as bolts 122.The front cover member 116 is secured, such as by welding at 124, to theimpeller assembly 126 of the torque converter 110.

The impeller assembly 126 is fluidly connected in toroidal flowrelationship in a known manner with the turbine assembly 128 and thestator assembly 130. The impeller assembly 126 comprises a plurality ofcircumferentially spaced impeller blades 132 connected to the inside ofan impeller shell 134. The impeller shell 134 is secured, such as bywelding at 136, to an impeller hub or pump drive shaft 138. The impellerhub 138 is drivingly engaged at its neck portion 140 to the positivedisplacement pump 200, from which fluid is supplied to the torqueconverter 110 in a manner to be described herein. An arcuate innerportion 142 of the impeller blade 132 is disposed about one half of asplit torus ring 144 which reduces fluid turbulence within the torqueconverter 110. A thrust plate 146 is connected by tabs (not shown) onthe inner surface of a slot 148 of the impeller hub 138 and disposedbetween the impeller assembly 126 and a stator thrust member 165.

The stator assembly 130 includes a plurality of circumferentially spacedstator vanes 150 which are connected at their inner end to a statorplate 152. The stator plate 152 is mounted on a one-way or over-runningclutch assembly, generally indicated at 154. The over-running clutchassembly 154 permits rotation only in the direction of the impellerassembly 126. The over-running clutch assembly 154 comprises anover-running clutch cam 156 mounted about over-running clutch rollers158, which in turn, travel about an over-running clutch race 160. Theover-running clutch race 160 is splined at inner surface 162 to astationary reaction shaft member 164. An annular thrust member 165having retaining transverse flanges or tabs 167 is disposed between thestator plate 152 and the thrust plate 146.

The turbine assembly 128 includes a plurality of circumferentiallyspaced turbine blades 166 which are connected to the inside of a turbineshell 168. The turbine shell 168 is secured by rivets 170 or the like toa turbine hub member 172. The turbine hub member 172 is drivinglyconnected, as by a spline connection 174, to a rotatable input member orshaft 176 to which the gear assembly 500 of the transmission 100 isdrivingly engaged. A turbine hub seal 178 is disposed between the insideof the turbine hub member 172 and the input shaft 176 to prevent entryof fluid therebetween. A cover bushing 180 having grooves (not shown)for fluid flow therethrough supports the turbine hub member 172 in acavity 182 of the front cover member 116. A thrust plate or washer 184having grooves (not shown) for fluid flow therethrough is disposedbetween the turbine hub member 172 and the front cover member 116. Anannular stepped member 185 having grooves (not shown) for fluid flowtherethrough is disposed between the turbine hub member 172 and statorplate 152, as well as the over-running clutch race 160.

The torque converter 110 also includes a lock-up clutch assembly,generally indicated at 186, to prevent slip between the rotatingcrankshaft 114 of the engine and the turbine assembly 128 of the torqueconverter 110. The lock-up clutch assembly 186 includes an annularpiston member 188 having an inner flange portion 190 disposed about theturbine hub member 172 of the turbine assembly 128. The piston member188 has a plurality of circumferentially spaced inverted U-shaped outerflange portions 192 which are formed to engage corresponding slots 194in a drive ring 196 that is welded to the turbine shell 168. The pistonmember 188 is slidingly and sealingly mounted for axial movement on theouter axial surface of the turbine hub member 172 through annular sealelement 198. An annular disc-shaped frictional element or lock-up disc199 is carried proximate the outer periphery of the front cover member116 for engagement with a cooperating portion of the piston member 188.

PUMP ASSEMBLY STRUCTURE

The fixed positive displacement pump assembly 200 includes a pumphousing 202 secured proximate its inner periphery to a reaction shaftsupport 204 by suitable fastening means such as bolts 206. The pumphousing 202 is likewise secured proximate its outer periphery to thetransmission case 102 by suitable fastening means such as bolts 208. Thereaction shaft support 204 is secured, such as by press fitting withsplines at 210, to the reaction shaft member 164. The impeller hub orpump drive shaft 138 is supported in the pump housing 202 through abushing member 212. A seal ring assembly 214 is disposed about theimpeller hub or pump drive shaft 138 in a bore or recess 216 at one endof the pump housing 202 to prevent fluid from exiting the end of thepump housing 202. An outer gear or rotor 218 with internal teeth (notshown) operates within a bore 220 of the pump housing 202. An inner gearor rotor 222 having external teeth (not shown), cooperative with theteeth of the outer rotor 218, is disposed within the outer rotor 218. Asillustrated in FIGS. 1C and 1D, sealing means, such as seal rings 224,226 and 228, are axially spaced between the input shaft 176 and reactionshaft support 204. The reaction shaft support 204 includes a fluidpassage 230 to allow fluid to flow to the torque converter 110 in amanner to described herein.

MULTI-CLUTCH ASSEMBLY STRUCTURE

During the flow of power through the transmission 100, the multi-clutchassembly 300 provides a means for application and release of twoseparate members to and from each other. In other words, themulti-clutch assembly 300 is the means by which the gears within thetransmission are selectively engaged and disengaged from either thecrankshaft 114 of the prime mover or the transmission case 102. Near theinput side of the transmission 100, the multi-clutch assembly 300includes an underdrive clutch 302 (applied in first, second and thirdgears), overdrive clutch 304 (applied in third and fourth gears) and areverse clutch 306 (applied in reverse gear) assemblies. Near the outputside of the transmission 100, the multi-clutch assembly 300 includes atwo/four shift clutch assembly 308 (applied in second and fourth gears),and a low/reverse clutch assembly 310 (applied in first and reversegears).

As illustrated in FIGS. 1C and 1D, an input clutch retainer hub 312 isprovided to house the input clutch assemblies 302, 304 and 306. Theinput clutch retainer hub 312 has a generally axially extending shoulderportion 313 and a generally axially extending portion 314. A pluralityof spaced seal rings 315 are disposed in corresponding annular grooves316 which are formed along the reaction shaft support 204. The inputclutch retainer hub 312 is also splined at 317 to the input shaft 176. Athrust bearing 318 is disposed axially between one end of the reactionshaft support 204 and the axially extending portion 314 of the inputclutch retainer hub 312. The input clutch retainer hub 312 has teeth 319at its outer periphery. A turbine speed sensor 320 threadably engages abore 322 in the transmission case 102 and has one end 324 disposed orspaced radially just above the teeth 319 of the input clutch retainerhub 312. The turbine speed sensor 320 is used to monitor or sense therevolution rate of the turbine assembly 128 by counting the teeth 319passing thereby in relation to time. Preferably, a passive type speedsensor is used for the turbine speed sensor 320. However, it should beappreciated that other suitable speed sensors could be employed withinor before the transmission 100 to provide an input speed signal for thetransmission controller 3010 to be described in connection with FIGS.28A-G.

An input clutch retainer 326 has a hub portion 328 disposed about anddrivingly connected to, as by a spline connection 330, to the axiallyextending portion 314 of the input clutch retainer hub 312. Sealingmeans, such as sealing rings 332 and 334, are disposed in correspondinggrooves of the input clutch hub retainer 312 between the hub portion 328and the axially extending portion 314 of the input clutch retainer hub312. A tapered snap ring 336 is disposed in a groove 338 of the inputclutch retainer hub 312 to prevent axial movement of the input clutchretainer 326 toward the gear assembly 500. The input clutch retainer 326includes an axially extending flange 340 forming a cylinder. A pluralityof circumferentially spaced clutch retainer fingers 341 extend radiallyinwardly from the flange 340 to which the clutch plates, which will bedescribed herein, are mounted.

As illustrated in FIG. 1D, the underdrive clutch assembly 302 comprisesa plurality of axially spaced annular clutch plates 342 and a pluralityof axially spaced annular clutch discs 344. The clutch discs 344 arealternated between the clutch plates 342 and when the clutch assembly302 is not applied, these plates and discs are free to move or rotaterelative to each other. The clutch plates 342 have splines (not shown)on their outer diameter and mount in grooves 346 of the clutch retainerfingers 341 which are inside the input clutch retainer 326. The clutchdiscs 344 have internal splines (not shown) and are lined with afriction material 347. The clutch discs 344 are mounted in grooves 348in an underdrive clutch hub 350. The underdrive clutch hub 350 isintegral with a rotatable underdrive gear shaft 352 of the gear assembly500. A thrust bearing 353 is disposed axially between the axiallyextending portion 314 of the input clutch retainer hub 312 andunderdrive clutch hub 350.

The overdrive clutch assembly 304 comprises a plurality of axiallyspaced annular clutch plates 354 and a plurality of axially spacedannular clutch discs 356. The clutch plates 354 and clutch discs 356 aresimilar to those of the underdrive clutch assembly 302. Clutch discs 356are disposed in splines formed in an overdrive clutch hub 358 which issupported by bushings 360 and 361 about the gear shaft 352. Thrustmembers 362 and 363 are disposed axially between the underdrive clutchhub 350 and overdrive clutch hub 358. The thrust members 362 and 363 aresimilar to the thrust member 165. An annular reaction plate 364 issecured to the inside of the input clutch retainer 326 axially betweenthe underdrive and overdrive clutch plates and discs 342, 344 354 and356, respectively. The reaction plate 364 is shared by the underdrive302 and overdrive 304 clutch assemblies. Annular snap rings 366 and 368are disposed on the sides of the reaction plate 364. Snap ring 368 is atapered ring, restraining reaction plate 364 from axial movement.

The reverse clutch assembly 306 comprises at least one annular clutchplate 370 and a plurality of axially spaced annular clutch discs 372.The reverse clutch plate 370 and clutch discs 372 are similar to thoseof the underdrive clutch assembly 302. The reverse clutch discs 372 aremounted in splines 373 of a reverse clutch hub 374. The reverse clutchhub 374 is supported by bushings 376 and 378 about one end of theoverdrive clutch hub 358. A thrust member 379 is disposed axiallybetween the overdrive clutch hub 358 and reverse clutch hub 379. Thethrust member 379 is similar to the thrust member 165. An annularreaction plate 380 is mounted about one end of the flange 340 of theinput clutch retainer 326 on one side of the reverse clutch plate 370and discs 372. Selective snap rings 384 secure the reaction plate 380from axial movement along the input clutch retainer 326.

To apply the overdrive clutch assembly 304 and reverse clutch assembly306, a fluid actuating device such as a first hydraulic piston 386 hasan axially extending projection 388 which operates in a bore or recess390 of the input clutch retainer hub 312. The inner diameter of theprojection 388 has a groove 392 provided for a snap ring 394, while therecess 390 of the input clutch retainer hub 312 has a groove 396 for asealing means such as a synthetic rubber seal ring 398. The firsthydraulic piston 386 is slidingly and sealingly mounted for axialmovement on the outer diameter of the hub portion 328 of the inputclutch retainer 326 through sealing means 400 at its inner periphery andnear the outer periphery of the input clutch retainer 326 throughsealing means 402. A double-acting spring means such as a Bellevillelike spring 404 is disposed between the first hydraulic piston 386 andthe input clutch retainer hub 312 to bias or return the first hydraulicpiston 386 to its non-displaced or non-applied position shown in thefigure. The double-acting spring 404 has a conical shape with fingers405 and is formed with a linear slope such that its inner and outerdiameters do not lie in the same cross-sectional plane. Thedouble-acting spring 404 will be discussed more in detail under thesection heading "DOUBLE-ACTING SPRING".

The first hydraulic piston 386 includes an axially extending cylinderportion 406 which has an annular pressure plate member 408 secured atone end thereof by waved snap ring 409a and snap ring 409b. A pressureplate member 408 is interposed between the overdrive clutch assembly 304and the reverse clutch assembly 306 to engage the clutch plates 354, 370and discs 356, 372, respectively. Hence, the single pressure platemember 408 is shared by the overdrive clutch 304 and reverse clutch 306assemblies.

To engage or disengage the underdrive clutch assembly 302, a secondhydraulic piston 410 operates in a recess 412 of the input clutchretainer 326. The smooth outer diameter of the hub portion 314 of theinput clutch retainer hub 312 has a groove 414 provided with a sealingmeans such as a synthetic rubber inner seal ring 416, while the outerperiphery of recess 412 has a groove 418 for an outer seal ring 420. Thesecond hydraulic piston 410 has one end 422 abutting the clutch plates342 of the underdrive clutch assembly 302. An annular conically shapedspring retainer member 424 is abuttingly mounted against a snap ring426. The snap ring 426 is disposed in a groove 428 formed in the axiallyextending portion 314 of the input clutch retainer hub 312. The otherend of the spring retainer member 424 is in sealing engagement with thesecond hydraulic piston 410 through sealing means 430. The springretainer member 424 is filled with fluid fed through an orifice (notshown) in the second hydraulic piston 410 from a passage (not shown) inthe input clutch retainer hub 312 to provide the pressure balance forthe second hydraulic piston 410. The excess fluid is allowed to leakpast the snap ring 426 to cool the underdrive clutch assembly 302. Aspring means such as a coiled spring 432 is disposed between the springretainer member 424 and the second hydraulic piston 410 to bias orreturn the second hydraulic piston 410 to its original position shown inthe figure when not applied.

At the output end of the transmission 100, the transmission case 102houses the output or brake clutch assemblies such as the two/four shiftclutch assembly 308 and the low/reverse clutch assembly 310. Thetwo/four shift clutch assembly 308 comprises a plurality of axiallyspaced annular clutch plates 434 and a plurality of axially spacedannular clutch discs 436. The clutch plates 434 and clutch discs 436 aresimilar to those of the underdrive clutch assembly 302. The clutchplates 434 are mounted in splines 438 of circumferentially spaced andradially inwardly extending case clutch fingers 439 inside thetransmission case 102. The clutch discs 436 are mounted in splines 440formed in an axially extending flange 442 of the reverse clutch hub 374.A spring means such as a Belleville like spring 444, similar to spring404, is mounted inside the transmission case 102 on one side of thetwo/four shift clutch assembly 308. An annular reaction plate 445 ismounted on the other side of the two/four shift clutch assembly 308 andbetween the two/four shift clutch assembly 308 and the low/reverseclutch assembly 310. The reaction plate 445 is shared by the two/fourshift clutch 308 and low/reverse clutch 310 assemblies. Snap rings 446and 447 are mounted in the transmission case 102 on the sides of thereaction plate 445 to lock it in place. Snap ring 446 is a tapered ring,restraining reaction plate 445 from axial movement.

To apply the two/four shift clutch assembly 308, a third hydraulicpiston 448 operates in a cavity 450 formed by an annular piston housing452. The piston housing 452 is secured to the transmission case 102 bysuitable fastening means (not shown). The smooth diameter of the thirdhydraulic piston 448 has a groove 454 formed in its outer periphery foran outer seal ring 456 and a groove 458 formed in its inner peripheryfor an inner seal ring 460. A snap ring 462 is disposed in a groove 464in the transmission case 102 to prevent axial movement of the pistonhousing 452.

The low/reverse clutch assembly 310 comprises a plurality of axiallyspaced annular clutch plates 466 and a plurality of axially spacedannular clutch discs 468. The clutch plates 466 and clutch discs 468 aresimilar to those of the underdrive clutch assembly 302. The clutchplates 466 are mounted in splines 470 of the case clutch fingers 439inside the transmission case 102. The clutch discs 468 are mounted insplines 472 of the outer periphery of an annulus gear 542 of the gearassembly 500 to be described further herein.

To apply the low/reverse clutch assembly 310, a fourth hydraulic piston474 operates in a cavity 476 formed by an annular piston housing 478.The piston housing 478 is disposed in an annular recess 480 of thetransmission case 102 and secured by suitable fastening means, such asbolts 481, to the transmission case 102. The smooth diameter of thefourth hydraulic piston 474 has a groove 482 formed in its outerperiphery for an outer seal ring 484 and a groove 486 formed in itsinner periphery for an inner seal ring 488. A spring means such as aBelleville like spring 490, similar to spring 404, is disposed betweenthe fourth hydraulic piston 474 and the gear assembly 500 to bias orreturn the fourth hydraulic piston 474 to its original position when notapplied as shown in the figure. A snap ring 492 retains one end of thespring 490 to the transmission case 102.

GEAR ASSEMBLY STRUCTURE

During the flow of power, the gear assembly 500 changes the ratio oftorque between an input member, such as input shaft 176, and an outputmember, such as output gear 534 which will be further described herein.The gear assembly 500 comprises a front or first planetary gear set,generally indicated at 502, and an axially spaced rear or secondplanetary gear set, generally indicated at 504. The first planetary gearset 502 includes a first sun gear 506 at its center. The first sun gear506 is connected to the reverse clutch hub 374 at its inner peripheryand is supported upon bushings 376 and 378. A first planet carrier 508is disposed about the first sun gear 506. The first planet carrier 508includes a plurality of circumferentially spaced first pinion gears 510mounted about shafts 512 connected to the first planet carrier 508. Thefirst planet carrier 508 includes an inner portion 514 splined at 516 tothe overdrive clutch hub 358. A thrust bearing 517 is disposed axiallybetween one end of the first sun gear 506 and inner portion 514 of thefirst planet carrier 508. The first planet carrier 508 also includes anaxially extending outer portion 518 forming a cylinder about the firstplanetary gear set 502. A first annulus gear 519 is disposed about thefirst planet carrier 508 and engages the first pinion gears 510.

The rear or second planetary gear set 504 includes a second sun gear 520at its center which is splined at 522 to the gear shaft 352. A thrustbearing 523 is axially disposed between one end of the inner portion 514of the first planet carrier 508 and the second sun gear 520. A secondplanet carrier 524 is disposed about the second sun gear 520. The secondplanet carrier 524 includes a plurality of circumferentially spacedsecond pinion gears 526 mounted about shafts 528 connected to the secondplanet carrier 524. The second planet carrier 524 includes an innerportion 530 splined at 532 to a rotatable output gear 534 which acts asthe output member of the transmission 100. The inner portion 530 of thesecond planet carrier 524 is supported by a bushing 536 disposed aboutthe second sun gear 520. A thrust bearing 537 is disposed axiallybetween the second sun gear 520 and second planet carrier 524. A taperedroller bearing assembly 538 supports the inner portion 530 of the secondplanet carrier 524 within the transmission case 102.

The second planet carrier 524 also includes an outer portion 540connected to the first annulus gear 519. The second annulus gear 542 isdisposed about the second planet carrier 524 and engages the secondpinion gears 526. The second annulus gear 542 is connected to the outerportion 518 of the first planet carrier 508.

The second planet carrier 524 includes teeth 544 at its outer peripheryof the outer portion 540. An output speed sensor 546 threadably engagesa bore 548 in the transmission case 102 and has one end 550 disposed orradially spaced just above the teeth 544 of the second planet carrier524. The output speed sensor 546 is used to monitor or sense therevolution rate (per minute) of the second planet carrier 524 bycounting or sensing the teeth 544 passing thereby relative to time. Theoutput speed sensor 546 is similar to the turbine speed sensor 320. Itshould also be noted that other suitable speed sensors could be usedinside or after the transmission 100 to provide an output speed signalto the transmission's controller 3010.

The output gear 534 is secured to the second planet carrier 524 bysuitable fastening means such as a bolt 552. The output gear 534 issupported by a tapered roller bearing assembly 554 within thetransmission case 102. A rear cover plate member 556 is connected bysuitable fastening means (not shown) to the rear or output end of thetransmission case 102 to enclose the output gear 534 and the transfergear (not shown).

To visualize and understand how power is transmitted from the rotatingcrankshaft 114 of the engine to the output gear 534 of the transmission100, the operation of the assemblies described above will now bediscussed in connection with FIGS. 1C, 1D and 1E.

OPERATION OF THE TORQUE CONVERTER

Rotation of the crankshaft 114 of the engine causes the front covermember 116 to rotate with it due to the connection between bolts 120,plate member 118 and bolts 122. Since the front cover member 116 iswelded at 124 to the impeller shell 134 of the impeller assembly 126,the impeller assembly 126 also rotates with the crankshaft 114. Thefluid within the impeller assembly 126 is set into motion by therotation of the impeller assembly 126 and by the fluid pressure from thepump assembly 200. The impeller blades 132 start to carry the fluidaround with them. As the fluid is spun around by the impeller blades132, it is thrown outward by centrifugal force and into the turbineassembly 128 at an angle. The fluid strikes the turbine blades 166 ofthe turbine assembly 128, thus imparting torque, or turning effort tothe turbine assembly 128 and causing the turbine shell 168 and theturbine assembly 128 to rotate. Since the turbine shell 168 is connectedto the turbine hub 172 through rivets 170 and the turbine hub 172 issplined at 174 to the input shaft 176, the input shaft 176 is caused torotate. As engine speed is increased, the force of the fluid strikingthe turbine blades 166 is also increased. Thus, torque is imparted tothe input shaft 176 of the transmission 100 via the turbine assembly128.

In the torque converter 110, the stator assembly 130 redirects the fluidflow so that the turbine blades 166 will have more force exerted uponthem during a torque multiplication stage. During torque multiplication,the over-running clutch assembly 154 in the stator assembly 130 islocked in a known manner so that the stator assembly 130 will remainstationary. As the fluid passes from the turbine assembly 128 to theimpeller assembly 126, the stator blades 150 of the stator assembly 130"push" the fluid against the impeller blades 132 so that a greater entryangle is imparted to the turbine blades 166, resulting in a greaterforce on the blades 166 and increasing the torque to the input shaft 176of the transmission 100.

The over-running clutch assembly 154 also permits the stator assembly130 to rotate only in the same direction as the impeller assembly 126.The over-running clutch assembly 154 resists torque in one direction forthe purpose of making the stator plate 152 and stator vanes 150stationary. This is accomplished by the clutch rollers 158 engagingradially narrowing recesses (not shown) in the over-running clutch cam156 to cause the over-running clutch cam 156, rollers 158 and race 160to form a single unit. Since the over-running clutch race 160 is splinedat 162 to the reaction shaft 164 which, in turn, is welded at 210 to thereaction shaft support 204 which cannot rotate, the over-running clutchcam 156, rollers 158 and race 160 remain stationary, resulting in thestator plate 152 and vanes 150 remaining stationary. The over-runningclutch assembly 154 allows the stator plate 152 and vanes 150 to rotatefreely in the opposite direction when their function as a reactionmember is not desired because the rollers 158 do not engage therecesses, resulting in the over-running clutch cam 156 rotating freelyabout the clutch race 160.

OPERATION OF TORQUE CONVERTER LOCK-UP

The lock-up function of the torque converter 110 will now be described.Fluid flows through the center passage 175 of the input shaft 176 intothe cavity 182 of the front cover member 116. The turbine hub seal 178prevents leakage of the fluid back around the input shaft 176. The fluidin cavity 182 flows through slots (not shown) in the front cover bushing180 and the thrust washer 184 and against the lock-up piston 188. Thefluid pushes the portion 192 of the lock-up piston 188 off the frictiondisc 199, resulting in non-lock-up operation. At the same time, fluidfrom the pump assembly 200 flows through passage 230 in the reactionshaft support 204 and between the input shaft 176 and reaction shaftmember 164. This fluid flows through slots (not shown) in the steppedmember 185 and into the turbine 128, stator 130 and impeller 126assemblies of the torque converter 110. Fluid also flows from theseassemblies 126, 128 and 130 between the lock-up piston 188 and theturbine shell 168. Hence, during normal torque converter operation,fluid flow is acting on the opposite side of the lock-up piston 188,attempting to apply the lock-up piston 188. When the input shaft fluidis vented, the torque converter fluid pushes the lock-up piston 188against the front cover member 116 with the friction disc 199 sandwichedbetween the two elements. Engine torque can then go through the frontcover member 116 to the lock-up piston 188 and, in turn, to drive ring196 and turbine shell 168.

As will be appreciated, lock-up of the torque converter 110 is desirableto reduce or eliminate rotational speed difference or "slip" between thecrankshaft 114 of the engine and the input shaft 176 of the transmission100. Lock-up of the torque converter 110 may be partial or full lockup.Partial lockup will reduce slip to predetermined value. Full lockup willeliminate slip or reduce it to a zero value. Lockup of the torqueconverter 110 may occur in second, third and fourth gears. Themethodology for lock-up of the torque converter 110 will be described inmore detail below, particularly with reference to FIG. 17.

OPERATION OF PUMP

The general operation of the pump assembly 200 will now be described.Specific fluid flow from the pump 200 to various assemblies in thetransmission 100 will be described in other sections herein.

The pump 200 creates flow and applies force to the fluid. As describedpreviously, the impeller shell 134 is welded at 136 to the impeller hub138 which acts as the pump drive shaft of the pump assembly 200.Rotation of the impeller shell 134 results in rotation of the impellerhub 138. Thus, the external source of power for the pump 200 is theengine.

In the pump assembly 200, both rotor members 218 and 222 rotatetogether. The inner rotor 222 is splined at 140 to the impeller hub 138and, therefore, rotates as the impeller hub 138 rotates. As the innerrotor 222 rotates or drives the outer rotor 218, a space (not shown)between the rotors 218, 222 increases as the rotor teeth separate andpass an outlet port (not shown).

In the pump assembly 200, a crescent-shaped protrusion (not shown) ofthe pump housing 202 divides the rotors 218 and 222. Fluid is trappedbetween the protrusion and the rotor teeth as it is carried to theoutlet port for further use in a manner to be described in othersections herein.

OPERATION OF THE CLUTCHES

As described previously, the input shaft 176 of the transmission 100 isrotating due to torque being transferred from the rotating crankshaft114 of the engine and through the torque converter 110 to the inputshaft 176. The input clutch retainer hub 312 also rotates with the inputshaft 176 due to its spline connection 317 with the input shaft 176. Theinput clutch retainer 326 and clutch plates 342, 354 and 370 also rotatewith the input shaft 176 due to the spline connection 330 of the inputclutch retainer 326 to the input clutch retainer hub 312 and splineconnection of clutch plates 342, 354 and 370 to the input clutchretainer 326.

To apply the underdrive clutch assembly 308, hydraulic pressure fromfluid entering between the input clutch retainer 326 and secondhydraulic piston 410 moves the second hydraulic piston 410 axially,thereby compressing the spring 432. The second hydraulic piston 410forces the rotating clutch plates 342 and momentarily stationary discs344 of the underdrive clutch assembly 302 together and producesfrictional force between the clutch plates 342 and discs 344. Becausethe input clutch retainer 326 and underdrive clutch plates 342 arerotating, the frictional force causes the underdrive clutch discs 344and hub 350 to rotate, in turn, rotating gear shaft 352 of the gearassembly 500. When the hydraulic fluid to the underdrive clutch assembly302 is vented, the compressed spring 432 applies a force to the secondhydraulic piston 410, thereby returning the second hydraulic piston 410to its non-applied position as shown in the figure.

To apply the overdrive clutch assembly 304, hydraulic pressure fromfluid entering between the first hydraulic piston 386 and the inputclutch retainer 326 moves or pulls the first hydraulic piston 386axially, thereby deflecting axially the spring 404. The pressure platemember 408 of the first hydraulic piston 386 forces the clutch plates354 and discs 356 of the overdrive clutch assembly 304 together againstthe reaction plate 364 and produces a frictional force between them.Because the input clutch retainer 326 and overdrive clutch plates 354are rotating, the frictional force causes the overdrive clutch discs 356and overdrive clutch hub 358 to rotate, in turn, rotating the firstplanet carrier 508 and second annulus gear 542. When the hydraulic fluidto the overdrive clutch assembly 304 or first hydraulic piston 386 isvented, the deflected spring 404 applies a force to the first hydraulicpiston 386, thereby returning the first hydraulic piston 386 to itsnon-applied position as shown in the figure.

To apply the reverse clutch assembly 306, hydraulic pressure from fluidentering between the first hydraulic piston 386 and input clutchretainer hub 312 moves or pushes the first hydraulic piston 386 axially,thereby deflecting the spring 404. The pressure plate member 408 of thefirst hydraulic piston 386 forces the clutch plate 370 and discs 372 ofthe reverse clutch assembly 306 together against the reaction plate 380and produces a frictional force between them. Because the input clutchretainer 326 and reverse clutch plate 370 are rotating, the frictionalforce causes the reverse clutch discs 372 and reverse clutch hub 374 torotate, in turn, rotating the first sun gear 506. When the hydraulicfluid to the reverse clutch assembly 306 or first hydraulic piston 386is vented, the deflected spring 404 applies a force to the firsthydraulic piston 386, thereby returning the first hydraulic piston 386to its non-applied position as shown in the figure.

At the output end of the transmission 100, the two/four shift clutch 308and low/reverse clutch 310 assemblies are used to hold a particular gearelement of the gear assembly 500 against rotation by coupling it to therelatively stationary transmission case 102. To apply the two/four shiftclutch assembly 308, hydraulic pressure from fluid entering between thethird hydraulic piston housing 452 and the third hydraulic piston 448moves the third hydraulic piston 448 axially, thereby deflecting thespring 444. The third hydraulic piston 448 forces the clutch plates 434and discs 436 of the two/four shift clutch assembly 308 together againstthe reaction plate 445 and produces a frictional force between them.Because the two/four clutch plates 434 do not rotate or are stationary,as they are connected to the transmission case 102, the frictional forceholds the two/four clutch discs 436 stationary, in turn, holding theflange 442, reverse hub member 374 and first sun gear 506 stationary.When the hydraulic fluid to the two/four shift clutch assembly 308 orthird hydraulic piston 448 is vented, the deflected spring 444 applies aforce to the third hydraulic piston 448, thereby returning the thirdhydraulic piston 448 to its non-applied position as shown in the figure.

To apply the low/reverse clutch assembly 310, hydraulic pressure fromfluid entering between the fourth hydraulic piston housing 476 and thefourth hydraulic piston 474 moves the fourth hydraulic piston 474axially, thereby deflecting the spring 490. The fourth hydraulic piston474 forces the clutch plates 466 and discs 468 of the low/reverse clutchassembly 310 together against reaction plate 445 and produces africtional force between them. Because the low/reverse clutch plates 466are stationary, as they are connected to the transmission case 102, thefrictional force holds the low/reverse clutch discs 468 stationary, inturn, holding the second annulus gear 542 and first planet carrier 508stationary. When the hydraulic fluid to the low/reverse clutch assembly474 or fourth hydraulic piston 474 is vented, the deflected spring 490applies a force to the fourth hydraulic piston 474, thereby returningthe fourth hydraulic piston 474 to its non-applied position as shown inthe figure.

OPERATION OF PLANETARY GEARS

In the neutral N or park P modes of transmission operation, the inputshaft 176 (which is attached to the turbine assembly 128) freely rotateswith the engine crankshaft 114. Since the input clutch retainer hub 312is also attached to the input shaft 176, the input clutch retainer hub312 rotates, in turn, causing the input clutch retainer 326 and clutchplates 342, 354 and 370 to freely rotate with the engine crankshaft 114.

When the transmission 100 is desired to operate in first gear, theunderdrive clutch assembly 302 and low/reverse clutch assembly 310 areapplied. Hydraulic fluid moves the second hydraulic piston 410 axiallyaway from the torque converter 110 to engage the clutch plates 342 andfriction discs 344 of the underdrive clutch assembly 302. Thisengagement causes the underdrive clutch hub 350 to rotate which, inturn, rotates the gear shaft 352. Because the second sun gear 520 issplined at 522 to the gear shaft 352, rotation of the gear shaft 352causes the second sun gear 520 to rotate. As the low/reverse clutchassembly 310 is applied by the engagement of the low/reverse clutchplates 466 with the discs 468, the second annulus gear 542 is heldstationary. Since the second annulus gear 542 is connected to the firstplanet carrier 508, the first planet carrier 508 is held stationary. Asa result, rotation of the second sun gear 520 causes rotation of thesecond pinion gears 528 and the second planet carrier 524. Because theoutput gear 534 is splined at 532 to the second planet carrier 524,rotation of the second planet carrier 524 causes the output gear 534 torotate. Since the second planet carrier 524 rotates, the first annulusgear 519 also rotates, causing the first pinion gears 510 and first sungear 506 to freely rotate in first gear. The output gear 534 thentransfers the torque from the second planetary carrier 524 to thetransfer gear (not shown).

When the transmission 100 is desired to operate in second gear, theunderdrive clutch assembly 302 and the two/four shift clutch assembly308 are applied. Once again, the underdrive clutch hub 350 rotates asdescribed above which, in turn, rotates the gear shaft 352. Rotation ofgear shaft 352 causes the second sun gear 520 to rotate. As the two/fourshift clutch assembly 308 is applied by engagement of the two/four shiftclutch plates 434 with the discs 436, the flange 442, reverse clutch hub374 and first sun gear 506 are held stationary. Because the transmission100 has been operating in first gear, the first annulus gear 519 andsecond planet carrier 524 have been rotating at output speed. Also, thefirst sun gear 506 has been rotating freely. By holding the first sungear 506 stationary, the first pinion gears 510 and first planet carrier508 increase in speed. As a result, the first annulus gear 519, secondplanet carrier 524 and the output gear 534 rotate at a greater r.p.m.than first gear.

When the transmission 100 is desired to operate in third gear, theunderdrive clutch assembly 302 and the overdrive clutch assembly 304 areapplied. Once again, engagement of the underdrive clutch assembly 302causes the second sun gear 520 to rotate as previously described. As theoverdrive clutch assembly 304 is applied by engagement of the clutchplates 354 and discs 356 of the overdrive clutch assembly 304, theoverdrive clutch hub 358 rotates, in turn, rotating the first planetcarrier 508 due to the spline connection at 516. Since the first planetcarrier 508 rotates, the first pinion gears 510, first sun gear 506 andsecond annulus gear 542 also rotate. As a result, the second piniongears 526 of the second planet carrier 524 rotate, causing the secondplanet carrier 524 to rotate which, in turn, rotates the output gear 534at input speed or a higher r.p.m. than second gear.

When the transmission 100 is desired to operate in fourth gear, theoverdrive clutch assembly 304 and two/four shift clutch assembly 308 areapplied. Application of the overdrive clutch assembly 304 causes theoverdrive clutch hub 358 to rotate, as previously described. Rotation ofthe overdrive clutch hub 358 causes the first planet carrier 508 andsecond annulus gear 542 to rotate. Application of the two/four shiftclutch assembly 308 causes the flange 442, reverse clutch hub 374 andfirst sun gear 506 to be held stationary as previously described. As aresult, rotation of the first planet carrier 508 causes the first piniongears 510, first annulus gear 519 and second annulus gear 542 to rotate.Rotation of the first and second annulus gears 519 and 542,respectively, causes the second pinion gears 526 and second planetcarrier 524 to rotate which, in turn, rotates the output gear 534 at agreater r.p.m. than third gear.

When the transmission 100 is desired to operate in reverse gear, thereverse clutch assembly 306 and low/reverse clutch assembly 310 areapplied. The reverse clutch assembly 306 is applied by engagement of thereverse clutch plate 370 and discs 372. This engagement causes thereverse clutch hub 374 to rotate which, in turn, rotates the first sungear 506. Application of the low/reverse clutch assembly 310 causes thefirst planet carrier 508 and the second annulus gear 542 to be heldstationary as previously described. As a result, the first sun gear 506rotates the first pinion gears 510 which, in turn, rotate the firstannulus gear 519 backwards. Rotation of the first annulus gear 519causes the second planet carrier 524 and second pinion gears 526 torotate which, in turn, causes rotation of the output gear 534 in adirection opposite to the other gear positions. Rotation of the secondpinion gears 526 also causes the second sun gear 520 to rotate freely.

CLUTCH REACTION AND APPLY PLATES

Referring to FIG. 1D, the reaction plate 380 and pressure plate member408 are shown. The present invention features web means such as anannular web 380a spaced radially at the outer periphery of the reactionplate 380 and connected to the reaction plate 380 at least one locationcircumferentially, and an annular web 408a spaced radially at the outerperiphery of the pressure plate member 408 and connected to the pressureplate member 408 at least one location circumferentially. The webs 380aand 408a are an efficient means of increasing axial rigidity to restrictclutch deflection. The reaction plate 380 and pressure plate member 408resist loads producing a stress pattern like that found in a Bellevillespring (i.e. producing a family of moments along the radial direction).

In a standard pressure or reaction plate, the highest stresses occur atthe outer diameter (OD) and inner diameter (ID) edges. The distributedloading by the clutch apply piston causes the plate to deflect to agenerally conical shape of some angle theta. With the addition of theannular web 380a, 408a, more material is being strained, resulting inlower stresses and less deflection theta. Thus, the addition of the web380a, 408a produces a plate having a stiffness comparable to the entirevolume from ID to OD of the reaction plate 380 or pressure plate member408 having been filled with material.

Additionally, the inside diameter of the annular web portion 380a isfitted closely with the outside diameter of clutch retainer fingers 341such that the fingers 341 and snap ring 384 are better supported(effectively stronger) against axial piston loading and centrifugallyinduced loads.

BLEEDER BALL CHECK VALVES

As illustrated in FIGS. 2A and 2B, the reaction shaft member 164 andreaction shaft support 204 are shown. The reaction shaft member 164 iswelded at 210 to the reaction shaft support 204. The reaction shaftsupport 204 comprises a plate portion 232 integral with a hub portion234. The plate portion 232 includes a pair of circumferentially spacedapertures 236 and 238. Each aperture 236 and 238 has a correspondingpassageway 240 communicating therewith and an outlet port 242. Bleedermeans such as bleeder ball check valves or dribblers, generallyindicated at 244 and 246, are disposed in apertures 236 and 238,respectively, to fill the clutch apply cavities 620 and 622 of theoverdrive 304 and reverse 306 assemblies, respectively, as soon aspossible after the input clutch retainer 326 begins to rotate and toassure that some fluid always dribbles thereto.

The bleeder ball check valves 244 and 246 each include a screen 248, aball support 250 disposed in the passageway 240 and a ball 252 supportedtherein. The ball 252 moves to open and close a narrow aperture ororifice 254 in the ball support 250. The screen 248 acts as a filter toprevent plugging of the orifice 254. The ball support 250 is also formedwith inwardly directed fingers 255 which limit the axial movement of theball 252. The bleeder ball check valves 244 and 246 allow one-way fluidflow to either the overdrive 304 or reverse 306 clutch assemblies,respectively. The size or diameter of the orifice 254 is selected tomaintain a minimum pressure, i.e. approximately 0.25 to 2 p.s.i., in theclutch apply cavities 620 and 622 at all times.

In operation, fluid flows from the torque converter 110 to reactionshaft support 204. When either clutch assembly 304, 306 is released,fluid enters apertures 236 or 238 in the plate portion 232 and flowsthrough the corresponding orifice 254 in ball support 250 due to thepressure differential between the fluid pressure from the torqueconverter 110 and the respective clutch apply cavity being vented. Fluiddisplaces and moves past the ball 252 to the overdrive 304 or reverse306 clutch assemblies. When the clutch apply cavity is filled, the fluidpressure moves the ball 252 to close the orifice 254 to preventbackflow. Thus, the bleeder ball check valves 236 and 238 provide fluidto keep the clutch apply cavities 620 and 622, respectively, filled andmaintain a pressure balance on the first hydraulic piston 386 wheneverrotation exists.

PRESSURE BALANCED PISTONS

Referring to FIG. 1B, the first hydraulic piston 386 includes at leastone bleeder orifice 256. The bleeder orifice 256 is typically 0.020inches in diameter and communicates axially through the first hydraulicpiston 386. A filter such as a screen 258 is disposed in the bleederorifice 256 to prevent plugging of the bleeder orifice 256 by dirt andother contaminants.

In operation, the first hydraulic piston 386 is displaced axially byfluid pressure in the clutch apply cavities 622 and 620 for theapplication of either the reverse 306 or overdrive 304 clutchassemblies, respectively. When that application is removed, the firsthydraulic piston 386 must return to its substantially centered ornon-applied position. Due to the centrifugal force acting on therotating fluid in either of the clutch apply cavities 620 or 622 whichapplied the piston 386, an unbalanced pressure will exist and cause thefirst hydraulic piston 386 to be biased and remain in that position eventhough the fluid apply line is vented. The bleeder orifice 256 acts as ameans to allow fluid to pass through the first hydraulic piston 386 dueto this differential pressure and allows the first hydraulic piston 386to be centered by the spring 404 since any centrifugal fluid pressure inthe clutch apply cavity is balanced by a comparable centrifugal fluidpressure on the opposite side when both clutch apply cavities 620 and622 are filled. The second hydraulic piston 410 has a similar bleedorifice (not shown) and secondary source of fluid to fill its pressurebalance cavity.

DOUBLE-ACTING SPRING

As illustrated in FIGS. 1C, 3A and 3B, a means such as a double-actingspring 404 locates and returns the first hydraulic piston 386. Thedouble-acting spring 404 is a Belleville like spring. The double-actingspring 404 is also annular and conically shaped with circumferentiallyspaced and inwardly extending fingers 405. The double-acting spring 404provides the advantage of saving space axially in the transmission 100due to its compactness. In other words, a conventional coil spring wouldincrease the axial length of the transmission 100 as compared to thedouble-acting spring 404.

The spring 404 is double-acting; that is, it is applied in twodirections at two different focal points. As illustrated in FIG. 3C,when the first hydraulic piston 386 is located or substantially centeredin its non-engaged or non-applied position between the input clutchretainer hub 312 and the input clutch retainer 326, the double-actingspring 404 maintains a four point contact. The double-acting spring 404contacts the snap ring 394, the shoulder portion 313 of the input clutchretainer hub 312, the inner periphery of the first hydraulic piston 386and one end of the hub portion 328 of the input clutch retainer 326.

When the first hydraulic piston 386 applies the overdrive clutch 304,the double-acting spring 404 is displaced toward the torque converter110. As illustrated in FIG. 3D, the double-acting spring 404 at itsouter periphery contacts the shoulder portion 313 of the input clutchretainer hub 312 and the inner periphery of the first hydraulic piston386. The double-acting spring 404 applies a return force toward itscentered position at the inner periphery of the first hydraulic piston386.

When the first hydraulic piston 386 applies the reverse clutch 306, thedouble-acting spring 404 is displaced axially in a direction away fromthe torque converter 110. As illustrated in FIG. 3E, the double-actingspring 404 contacts the snap ring 394 and the end of the hub portion 328of the input clutch retainer 326. The double-acting spring 404 applies areturn force toward its centered position at the snap ring 394.

In other words, double-acting spring 404 applies a force at its outerperiphery in the direction of the torque converter 110 to move the firsthydraulic piston 386 axially toward the torque converter 110. This focalpoint is located at the inner periphery thereof. The double-actingspring 404 also applies a force at its inner periphery in the directionof the output gear 534 to move the first hydraulic piston 386 toward theoutput gear 534. This focal point is located at the outer periphery ofthe double-acting spring 404.

Additionally, the double-acting spring 404 is preloaded either by thefirst hydraulic piston 386 or the input clutch retainer hub 312. Sincethe double-acting spring 404 usually bends as a cantilever beam, thepreloading of the spring 404 by the inner periphery of the firsthydraulic piston 386 produces a tip deflection at the outer periphery ofthe double-acting spring 404, resulting in a gap between the spring 404and the snap ring 394. Preloading at the shoulder 313 by the inputclutch retainer hub 312 produces a tip deflection in the oppositedirection, reducing the gap between the double-acting spring 404 andsnap ring 394 by a large amount. As a result, the double-acting spring404 will take some intermediate or statically indeterminate position,distributing the load to all four apply points previously described. Inother words, the axial lash in the piston position is removed by thedouble-acting spring 404 as it deforms to take a staticallyindeterminate position between the first hydraulic piston 386 and theinput clutch retainer hub 312.

LOW-EFFORT DOUBLE-ROLLER PARK SPRAG

The park locking mechanism positively locks the second planet carrier524 of the transmission 100 to the transmission case 102 when the parkoperating mode of the transmission 100 is manually selected by thedriver or operator of the vehicle. The present invention provides anautomatic transmission park locking mechanism designed to reduce to theleast possible extent the sliding friction and effort required toactuate the park locking mechanism.

Referring to FIGS. 4A through 4J, a low-effort double-roller parklocking mechanism or sprag 560 is shown. As illustrated in FIG. 4E, thepark sprag 560 includes a pawl lever or member, generally indicated at561, having a shape similar to the lower case letter "r". The pawlmember 561 includes a head portion 562. A planar edge portion 562a, asloping cam or ramp portion 562b and a pressure edge portion 562cprovide a cam surface, as will be explained below, engageable withrollers. One end 563 of the pawl member 561 is pivotally connected abouta dowel or pin 564 of the transmission case 102. The pawl member 561 issupported by the pin 564 between a retainer bracket, generally indicatedat 565. The retainer bracket 565 is U-shaped in cross-section andincludes an inwardly offset wall portion 565a joined to the principalwall portion 565b by an intermediate oblique or angled wall portion 565cto form a bracket wall. The angled wall portion 565c together with theprincipal 565b and offset 565a wall portions provide a cam surface forthe rollers to be described herein. The offset wall portion 565aterminates in a right-angled stop flange or end wall 565d (FIG. 4D). Theretainer bracket 565 includes a pair of side walls 566 extendingoutwardly from the bracket wall 565a, 565b, 565c.

Washers 567 and 568 are disposed about each side of the pawl member 561and the pin 564 between the side walls 566 of the retainer bracket 565.A spring means comprising a spring 569 is disposed about the pin 564 andhas one end engaging a second dowel or pin 570 of the transmission case102 and the other end engaging as step or shoulder 571 on the pawlmember 561. The spring 569 biases the pawl member 562 toward the offsetwall portion 565a of the retainer bracket 565.

The pawl member 561 cooperates with a rod assembly, generally indicatedat 572. The rod assembly 572 comprises a rod 573 having a cap member 574secured at one end. An attachment member 575 is disposed about the rod573. The attachment member 575 includes a shaft 576 disposed in anaperture 577 of a manual lever or rooster comb 578 and secured theretoby a snap ring 579. A spring 580 is disposed about the rod 573 betweenthe attachment member 575 and laterally extending projections 581 on therod 573. A more detailed description of the manual lever 578, manualvalve 604, shaft member 770, and cam groove 772 can be found undersection heading "CAM CONTROLLED MANUAL VALVE".

The other end of the rod 573 includes a pair of laterally adjacent camrollers 582 and 583 journally supported thereon by their associatedsupport pins 584 and 585, respectively, secured to a U-shaped carrier orbracket member 586, as illustrated in FIG. 4F. Each of the rollers 582,583 are formed with a central bore 584a and 585a, respectively. Eachbore 584a, 585a receive pins 584, 585, respectively, therethrough in anoversize manner such that each of the rollers 582 and 583 are free forpredetermined limited transverse movement relative to its associated pinso as to rollingly engage the remaining roller.

The U-shaped bracket member 586 includes an inclined projection 587extending outwardly parallel with the sides thereof. A projection 588extends outwardly from each side of the U-shaped bracket member 586 toguide the bracket member 586 between the sides of the retainer bracket565, as illustrated in FIG. 4G. The U-shaped bracket member 586 alsoincludes an inverted "L" shaped portion 590 at the bottom of the "U".

In operation, the pawl member 561 abuts the retainer bracket 565 due tothe biasing of the spring 569, as illustrated in solid lines in FIG. 4C,when the shift lever position is not park P. When a shift position orgear selector shaft 591 connected to the manual lever 578, asillustrated in FIGS. 4B and 4H, is moved to the park P position, the rod573 is moved. The rollers 582 and 583 roll along the principal wallportion 565b of the retainer bracket 565 and the pressure edge portion562c of the pawl member 561, respectively. The roller 583 engages a rampportion 562b of the pawl member 561 and the roller 582 engages theangled wall portion 565c of the retainer bracket 565, as illustrated inFIGS. 4C and 4D. This causes the pawl member 561 to be displaced orrotated about the pin 564. The rod 573 moves until one end of the headportion 562 of the pawl member 561 has engaged a space 592 between apair of adjacent teeth 544 in the second planet carrier 524 of the gearassembly 500 and the rollers 583 and 582 abut the planar edge portion562a of the pawl member 561 and the offset wall portion 565a of theretainer bracket 565 respectively as illustrated in solid lines in FIG.4A. The operation is reversed when the shift lever is in a positionother than the park P position.

The L-shaped portion 590 engages a slot 594 in a plate member 596connected to the valve body 603 of the transmission case 102 at theother extreme of the travel, the installation position (IN), asillustrated in FIGS. 4H, 4I and 4J, to limit the travel of the rodassembly 572. During assembly of the transmission 100, the installationposition prevents the rod assembly 572 from being moved and maintainingthe rod assembly 572 in axial alignment with the guide bracket 565.

When the shift lever position is park P position, the pawl member 561may not engage a space 592 between adjacent teeth 544 in the secondplanet carrier 524 as shown in FIG. 4D. In this case, the spring 580biases the rod 573 toward the end wall 565d of the bracket member 565.This causes the head portion 562 of the pawl member 561 to contact atooth 544 on the second planet carrier 524. When the vehicle rollsbackward, causing the second planet carrier 524 to rotate, the biasedspring 580 moves the rod 573 and, in turn, moves the head portion 562into the next available space 592 in the second planet carrier 524 tolock the second planet carrier 524 in place.

Accordingly, the park locking mechanism 560 provides cam rollers 582,583 with oversized bores 584a, 585b, respectively, to allow the rollers582, 583 to shift into load-bearing contact. Thus, the main reactionload applied by the offset wall portion 565a and the cam surface 562b ofthe pawl member 561 are transmitted first between the rollers 582, 583to the offset wall portion 565a and, in turn, to the transmission case102. Hence, substantially reduced reaction loads are transmitted to thepins 584, 585 so as to increase the service life of the pins 584, 585and rollers 582, 583.

HYDRAULIC SYSTEM STRUCTURE

The function of the hydraulic system is to cooperate with the electroniccontrols (FIGS. 28A through 28G) to make the transmission 100 fullyautomatic. Referring to FIGS. 5A through 5L, a schematic diagram of thehydraulic system 600 for controlling and operating the fluid flowthroughout the transmission 100 is shown. The pump assembly 200, clutchassemblies 302, 304, 306, 308 and 310, torque converter assembly 110 ofFIG. 1, and valves to be described herein, are connected by a pluralityof internal passageways, generally indicated at 602, in or between thevalve body 603 (FIG. 6), transfer plate (not shown) and transmissioncase 102.

The fluid source of the transmission 100 is the fluid contained in thetransmission pan (not shown) which acts as a reservoir. A filter 605 isattached to the lower half of a transfer plate at the inlet of thetransfer plate to prevent dirt and other foreign matter from enteringthe hydraulic system 600. Another filter (not shown) is disposed in thevalve body 603 at the pump pressure inlet to a pressure regulator valve608 to protect the pressure regulator valve 608 from any loose chips anddirt in the pump hydraulic circuit.

The pump assembly 200 is also connected by the passageways 602 to amanual valve 604 which is coupled to the manually actuated shift leveror manual shaft 591. The manual shaft 591 is connected to the manuallever 578 (FIG. 4B), its shift lever position PRNODDL being generallyindicated by numeral 606. The pump assembly 200 is further connected bypassageways 602 to a pressure regulator valve 608 and to a solenoid orfluid switch valve 610. The passageways 602 also connect the pressureregulator 608 to a cooler or torque converter (T/C) control valve 612.The passageways 602 also connect the T/C control valve 612 to a lock-up(LU) switch valve 614. The passageways 602 further connect the LU switchvalve 614 to the torque converter 110, and they also provide a path fromthe torque converter 110 back to the LU switch valve 614 and to T/Ccontrol valve 612. A cooler 616 is connected by passageways 602 to theT/C control valve 612. The manual valve 604 is also connected bypassageways 602 to an underdrive element or clutch apply cavity 618, anoverdrive clutch apply cavity 620, reverse clutch apply cavity 622 and atwo/four shift clutch apply cavity 624. A low/reverse clutch applycavity 626 is connected by passageways 602 to the solenoid switch valve610 and, in turn, to the manual valve 604.

The clutch apply cavities 618, 620, 622, 624 and 626 are also identifiedin FIGS. 1C and 1D. The valves 604 and 610 are also connected bypassageways 602 to a vent reservoir 628 in the manifold assembly 700(FIGS. 7-9) which is at a higher elevation than the sump or fluidreservoir in the transmission pan. The other valves vent to the sump asindicated by the letter "V".

The hydraulic system 600 also includes an underdrive element or clutchsolenoid-actuated valve 630, overdrive clutch solenoid-actuated valve632, two/four shift clutch solenoid-actuated valve 634 and low/reverseclutch solenoid-actuated valve 636 which will be described in connectionwith FIGS. 7-9. The solenoid-actuated valves 630, 632, 634 and 636control the fluid flow to their respective clutch apply cavities 618,620, 624 and 626.

The manual valve 604 controls the fluid flow to the reverse clutch applycavity 622. The low/reverse clutch solenoid-actuated valve 636 includesa second or dual function of controlling fluid flow to the LU switchvalve 614 during lock-up of the torque converter 110 (FIGS. 5G, 5I, 5J,5L). The two/four clutch solenoid-actuated valve 634 also has a dualfunction of controlling fluid flow to the low/reverse clutch applycavity 626 when the shift lever position 606 is reverse (FIG. 5C). Thesesolenoid-actuated valves 630, 632, 634 and 636 operate in response tocommand or control signals from the electronic controls.

In one embodiment according to the present invention, both theunderdrive clutch solenoid-actuated valve 630 and two/four shift clutchsolenoid-actuated valve 634 are designed to be normally applied. Thismeans that in the absence of electrical power, the solenoid-actuatedvalves 630 and 634 will allow pressure or fluid flow in the passageways602 to be transmitted to the underdrive clutch apply cavity 618 andtwo/four shift clutch apply cavity 624, respectively. Hence, theunderdrive clutch assembly 302 and two/four shift clutch assembly 308will be applied, resulting in the transmission 100 operating in secondgear. Likewise, the overdrive clutch solenoid-actuated valve 632 andlow/reverse clutch solenoid-actuated valve 636 are designed to benormally vented. This means that in the absence of electrical power, thesolenoid-actuated valves 632 and 636 will vent fluid in passageways 602and thus prevent fluid flow to the overdrive clutch apply cavity 620 andlow/reverse clutch apply cavity 626, respectively. Hence, the overdriveclutch assembly 304 and low/reverse clutch assembly 310 will not beapplied so that the transmission 100 may operate in second gear.

The hydraulic system 600 also includes accumulators 638, 640, 642 and644 which are connected to passageways 602 before the underdrive 618,overdrive 620, two/four shift 624 and low/reverse 626 clutch applycavities, respectively. As illustrated in FIG. 6, the accumulators 638,640, 642 and 644 comprise a first spring 645a, a second spring 645b anda piston 645c operating in a bore 645d in the valve body 603. Thepurpose of these accumulators 638, 640, 642 and 644 is to absorb thefluid apply pressure to help cushion the application of the underdrive302, overdrive 304, two/four shift 308 and low/reverse 310 clutchassemblies, respectively.

As illustrated in FIGS. 5A-5L, pressure switches 646, 648 and 650 areconnected to the passageways 602 which lead to the overdrive clutchapply cavity 620, the two/four shift clutch apply cavity 622 and thelow/reverse clutch apply cavity 626, respectively. The pressure switches646, 648 and 650 provide a digital electrical signal of zero (0) valuewhen there is either an absence of fluid pressure or fluid pressurebelow a predetermined pressure, and a value of one (1) when there isfluid pressure present at or above a predetermined pressure in thepassageway 602 leading to the respective clutch apply cavities 620, 624and 626. However, it should be appreciated that other suitable pressuresensors may be employed in these or other locations in the appropriateapplication.

The hydraulic system 600 also includes first 652, second 654, third 656,fourth 658 and fifth 660 ball check valves in the passageways 602leading to the low/reverse 626, underdrive 618, low/reverse 626, reverse622 and overdrive 620 clutch apply cavities, respectively. The ballcheck valves 652, 654, 656, 658 and 660 comprise a rubber ball operatingagainst a seat, typically formed in the valve body 603, and are used forflow control to open and close particular passageways 602. The ball isseated by pressure acting against the ball and unseated by pressurebeing applied on the opposite or seat side of the ball.

As illustrated in FIGS. 5A through 5L, the LU switch valve 614, T/Ccontrol valve 612 and pressure regulator 608 include springs 662, 664and 666, respectively, at one end to preload these valves. A thermalvalve 668 is also provided to regulate the fluid flow through checkvalve 654 at higher fluid temperatures. The thermal valve 668 closes oropens a particular passageway 602 based on the fluid temperature.

OPERATION OF THE HYDRAULIC SYSTEM

As illustrated in FIGS. 5A-L, the hydraulic system 600 is shown. Thedense shading or hatching in the passageways 602 shows fluid at pumppressure. The sparse shading or hatching illustrates a low fluidpressure. The intermediate shading or hatching illustrates a fluidpressure between that of pump pressure and a low pressure. The absenceof shading or hatching shows the passageways 602 as vented.

When the engine is initially started, the pressure regulator 608 isactuated or moved by fluid pressure to allow fluid from the pumpassembly 200 to flow through the pressure regulator 608 between thefirst 670a and second 670b lands to the T/C control valve 612, asillustrated in FIG. 5A. The T/C control valve 612 is similarly actuatedby fluid pressure to allow fluid from the pressure regulator 608 to flowbetween the first 672a and second 672b lands of the T/C control valve612 to the LU switch valve 614. Fluid then flows between the first 674aand second 674b lands of the LU switch valve 614 to the torque converter110. This fluid pressure moves the lock-up piston 188 off or indisengagement with the friction disc 199 of the lock-up clutch assembly186 so that lock-up is not applied. Fluid also flows from the torqueconverter 110 back to the T/C control valve 612. Fluid flows between thesecond 674b and third 674c lands thereof and through the cooler 616where it is cooled and used for lubrication.

As illustrated in FIG. 5A, when the shift lever position 606 is park Por neutral N with the output speed N_(o) from the transmission's outputspeed sensor 546 less than 600 r.p.m., fluid flows from the pumpassembly 200 to the manual valve 604. Fluid flows through the manualvalve 604 between the first 676a and second 676b lands to thelow/reverse clutch solenoid-actuated valve 636 which is energized by thetransmission controller 3010 and moves to allow fluid to flow through itto the solenoid switch valve 610. The solenoid switch valve 610 ishydraulic or fluid pressure operated for reciprocal movement between afirst position shown in FIG. 5E and a second position shown in FIG. 5F.

Fluid flows through the solenoid switch valve 610 between the second678b and third 678c lands thereof to the first ball check valve 652. Thefirst ball check valve 652 is moved by fluid pressure to close the flowpath to the vent through the manual valve 604 and opens the flow path tothe low/reverse clutch apply cavity 626. Fluid flows through the firstball check valve 652 to the low/reverse clutch apply cavity 626 behindthe fourth hydraulic piston 474 to apply the low/reverse clutch assembly310 in a manner controlled by the command signal from the transmissioncontroller 3010 sent to the low/reverse clutch solenoid-actuated valve636.

As illustrated in FIG. 5A, fluid flows from the manual valve 604 andsolenoid switch valve 610 to both sides of the third ball check valve656. In this case, the third ball check valve 656 is redundant.

The manual valve 604 also allows fluid in the clutch apply cavity 624 ofthe two/four shift clutch assembly 308 to vent to the vent reservoir628, resulting in this clutch not being engaged or applied. Similarly,fluid in the clutch apply cavity 618 of the underdrive clutch assembly302 is vented either through the manual valve 604 to the sump or throughthe underdrive clutch solenoid-actuated valve 630. Some fluid from thetorque converter 110 also flows through the bleeder ball check valves244 and 246 to the overdrive 620 and reverse 622 clutch apply cavitiesas previously described. However, the overdrive 304 and reverse 306clutch assemblies are essentially vented and not applied.

Fluid from the pump assembly 200 also flows to the solenoid switch valve610 at one end of the first land 678a to pressure balance solenoidswitch valve 610. In other words, fluid flow pressurizes one end of thesolenoid switch valve 610 to allow the valve to maintain its currentposition and prevent the valve from moving to one end or the other pastits desired or proper position. Fluid also flows from the pump assembly200 to the LU switch valve 614 between the third 674c and fourth 674dlands and is dead-ended. This is because the LU switch valve 614 is asingle diameter valve, therefore no resultant force exists to overcomethe spring force of spring 666. Additionally, fluid from the pumpassembly 200 flows to one end of a plug 680 of the pressure regulator608 to pressure balance the pressure regulator 608. Fluid from the pumpassembly 200 further flows to the two/four shift clutchsolenoid-actuated valve 634. However, this valve is energized by thetransmission controller 3010 and moves to block or close fluid flow tothe two/four shift clutch apply cavity 624.

As illustrated in FIG. 5B, when the shift lever position 606 is neutralN with the output speed N_(o) from the transmission's output speedsensor 546 greater than 600 r.p.m., fluid flows from the pump assembly200 to the manual valve 604. Fluid flows through the manual valve 604between the first 676a and second 676b lands to the third ball checkvalve 656. This fluid pressure moves the third ball check valve 656 toclose the flow path to the low/reverse clutch apply cavity 626. Hence,the low/reverse clutch assembly 310 is not applied, but vented throughthe first ball check valve 652 to either the low/reverse clutchsolenoid-actuated valve 636 or the manual valve 604. This prevents thetransmission 100 from being shifted into a drive mode OD, D or L abovean undesired output speed N_(o), i.e. 600 r.p.m. Fluid from the manualvalve 604 also flows to the low/reverse clutch solenoid-actuated valve636 which is off or de-energized (i.e. normally vented) and closes theflow path to the solenoid switch valve 610.

The manual valve 604 further allows fluid in the clutch apply cavity 624of the two/four shift clutch assembly 308 to vent to the vent reservoir628, resulting in this clutch not being engaged or applied. Fluid in theclutch apply cavity 618 of the underdrive clutch assembly 302 ventsthrough the underdrive clutch solenoid-actuated valve 630 to vent thereservoir 628, resulting in this clutch not being engaged or applied.The overdrive 304 and reverse 306 clutch assemblies receive some fluidbut are vented or not applied as previously described. Fluid from thepump assembly 200 also flows to one end of the first land 678a of thesolenoid switch valve 610 to hold it in a position for fluidcommunication by the passageways 602 between the low/reverse clutchsolenoid-actuated valve 636 and the clutch apply cavity 626 of thelow/reverse clutch assembly 310. Fluid also flows from the pump assembly200 to the LU switch valve 614 and pressure regulator 608 as previouslydescribed. Additionally, fluid from the pump assembly 200 further flowsto the two/four shift clutch solenoid-actuated valve 634. However, thisvalve is energized to block fluid flow as previously described.

As illustrated in FIG. 5C, when the shift lever position 606 is reverseR, the manual valve 604 attached to the manual lever 578 is moved orshifted. Fluid flows from the pump assembly 200 to the manual valve 604.Fluid flows through the manual valve 604 between the first 676a andsecond 676b lands and through an orifice 682 to the reverse clutch applycavity 622 between the second hydraulic piston 410 and input clutchretainer hub 312 to apply the reverse clutch assembly 306. Fluid flowsto both sides of the fourth ball check valve 658 making it redundant.However, the fourth ball check valve 658 allows fluid flow from thereverse clutch apply cavity 622 to bypass the orifice 682 when ventingthe reverse clutch apply cavity 622 through the manual valve 604.

The manual valve 604 also allows fluid in the clutch apply cavity 624 ofthe two/four shift clutch assembly 308 to vent to the vent reservoir628, resulting in this clutch not being engaged or applied. Fluid in theclutch apply cavity 618 of the underdrive clutch assembly 302 ventsthrough the underdrive clutch solenoid-actuated valve 630. The overdriveclutch assembly 304 receives some fluid but is vented or not applied aspreviously described. Fluid to the reverse clutch apply cavity 622causes the reverse bleeder ball check valve 246 to close as previouslydescribed.

Fluid from the pump assembly 200 flows through the two/four shift clutchsolenoid-actuated valve 634, which is not energized or applied normally,to the manual valve 604. Fluid flows through the manual valve 604between the third 676c and fourth 676d lands of the manual valve 604 tothe first ball check valve 652. This fluid pressure moves the first ballcheck valve 652 to close the flow path to the solenoid switch valve 610and opens the flow path to the low/reverse clutch apply cavity 626behind the fourth hydraulic piston 474 to apply the low/reverse clutchassembly 310. Fluid from the pump assembly 200 further flows to one endof the first land 678a of the solenoid switch valve 610 and the LUswitch valve 614 as previously described. Additionally, fluid flows toboth ends of the plug 680 of the pressure regulator 608. Since thepressure area of the plug 688 is smaller than plug 680, the valve 680 isshifted, creating a new fluid line pressure.

As illustrated in FIG. 5D, when the shift lever position 606 is reverseR and the output speed N_(o) is greater than 600 r.p.m., fluid flowsfrom the pump assembly 200 to the manual valve 604. Fluid flows throughthe manual valve 604 between the first 676a and second 676b lands andthrough the orifice 682 to the reverse clutch apply cavity 622 betweenthe second hydraulic piston 410 and the input clutch retainer hub 312 toapply the reverse clutch assembly 306. The two/four shift clutchsolenoid-actuated valve 634 is energized by the transmission controller3010 and moves to prevent fluid flow to the manual valve 604, resultingin the low/reverse clutch 310 not being applied. This prevents thetransmission 100 from being shifted into the reverse mode above anundesired output speed N_(o), i.e. 600 r.p.m.

Fluid in the clutch apply cavities 624, 618 and 620 of the two/fourshift clutch 308, underdrive clutch 302 and overdrive clutch 304assemblies, respectively, are vented as previously described, resultingin these clutches not being engaged or applied. The overdrive clutchassembly 304 receives some fluid but is vented or not applied aspreviously described. Otherwise, fluid flow is similar to the reversehydraulic schematic of FIG. 5C as previously described.

As illustrated in FIG. 5E, when the shift lever position 606 is thedrive D position, overdrive OD or low L, the transmission 100 isoperated initially in first gear. As a result, the manual valve 604 ismoved or shifted. Fluid flows from the pump assembly 200 to the manualvalve 604. Fluid flows through the manual valve 604 between the first676a and second 676b lands to the underdrive clutch solenoid-actuatedvalve 630. The underdrive clutch solenoid-actuated valve 630 which isnormally applied, allows fluid to flow through it and the flow path tothe underdrive clutch apply cavity 618 behind the second hydraulicpiston 410 to apply the underdrive clutch assembly 302.

Fluid from the manual valve 604 also flows to the second ball checkvalve 654 which is pressurized from both sides and becomes redundant.Fluid from the manual valve 604 moves the fifth ball check valve 660 toclose the flow path to the overdrive clutch apply cavity 620. Fluid fromthe manual valve 604 further flows to the overdrive clutchsolenoid-actuated valve 632 which is normally vented and is preventedfrom flowing through the flow path to the overdrive clutch apply cavity620.

Fluid further flows to both sides of the third ball check valve 656,making it redundant. Fluid from the manual valve 604 also flows to thelow/reverse clutch solenoid-actuated valve 636. The low/reverse clutchsolenoid-actuated valve 636 is energized by the transmission controller3010 and moves to open the flow path to the solenoid switch valve 610.Fluid flows through the solenoid switch valve 610 between the second678b and third 678c lands to the low/reverse clutch apply cavity 626behind the fourth hydraulic piston 474 to apply the low/reverse clutchassembly 310.

Fluid in the clutch apply cavity 624 of the two/four shift clutchassembly 308, is vented as previously described, resulting in thisclutch not being engaged or applied. Fluid in the clutch apply cavity620 of the overdrive clutch assembly 304 is vented through the overdriveclutch solenoid-actuated valve 632. Fluid in the clutch apply cavity 622of the reverse clutch assembly 306 is vented through the manual valve604. Hence, the overdrive 304 and reverse 306 clutch assemblies areessentially vented and not applied as previously described.

Fluid from the pump assembly 200 also flows to one end of the first land678a of the solenoid switch valve 610, the LU switch valve 614, and oneend of the plug 680 of the pressure regulator 608 as previouslydescribed. Fluid from the pump assembly 200 also flows to the two/fourshift clutch solenoid-actuated valve 634. However, this valve isenergized and moved to engage its seat to block fluid flow as previouslydescribed.

Referring to FIG. 5F, the operation of the hydraulic system isillustrated when the transmission 100 is shifted into second gear. Itshould be noted that none of the solenoid-actuated valves 630, 632, 634and 636 are energized, so that they will each assume their normally open(applied) or closed (vented) positions as described earlier.

As illustrated in FIG. 5F, when the shift lever position 606 is in theoverdrive OD, drive D or low L position, and the transmission 100 is tobe operated in second gear, the manual valve 604 remains in the sameposition as first gear. Fluid flows from the pump assembly 200 to themanual valve 604. Fluid flows through the manual valve 604 between thefirst 676a and second 676b lands to the underdrive clutchsolenoid-actuated valve 630 which is normally applied and allows fluidflow to the underdrive clutch apply cavity 618 as previously described.Fluid also flows from the manual valve 604 to the overdrive clutchsolenoid-actuated valve 632 which is normally vented and prevents fluidflow to the overdrive clutch apply cavity 620. Fluid from the manualvalve 604 also flows to the second and fifth ball check valves 654 and660 as previously described.

Fluid from the pump assembly 200 also flows to the two/four shift clutchsolenoid-actuated valve 634 which is normally applied and allows fluidflow to the manual valve 604. Fluid flows between the third 676c andfourth 676d lands of the manual valve 604 to the two/four shift clutchapply cavity 624 behind the third hydraulic piston 448 to apply thetwo/four shift clutch assembly 308. Fluid also flows between one end offifth land 678e of the solenoid switch valve 610 and a plug 684. Becausethe pressure area of area of fifth land 678e is larger than the pressurearea of first land 678a, when these lands 678a and 678e are exposed tothe same pressure, the solenoid switch valve 610 is moved to the left asshown in the figure. Hence, the solenoid switch valve 610 is moved byfluid pressure acting on it to allow fluid to flow through the solenoidswitch valve 610 between the fourth 678d and fifth 678e lands and to oneend of a plug 686 thereof to pressure balance the solenoid switch valve610.

Fluid in the clutch apply cavity 626 of the low/reverse clutch assembly308 is vented as previously described, resulting in this clutch notbeing engaged or applied. The overdrive 304 and reverse 306 clutchassemblies are also vented as previously described. Fluid from the pumpassembly 200 further flows through the LU switch valve 614 to one end ofplug 680 of the pressure regulator 608 as previously described.

As illustrated in FIG. 5G, when the partial lock-up feature is used insecond gear, the LU switch valve 614 is moved or shifted by fluidpressure, from the low/reverse clutch solenoid-actuated valve 636 andthe solenoid switch valve 610, to close fluid flow from the T/C controlvalve 612 to the lock-up clutch assembly 186 of the torque converter 110because it is dead-ended at second land 674b of the LU switch valve 614.This results in fluid flow from the lock-up clutch assembly 186 beingvented at the LU switch valve 614. Fluid flow from the pump assembly 200to the torque converter 110 causes the lock-up piston 188 to engage thefriction disc 199 of the torque converter 110. Lock-up of the torqueconverter 110 occurs as previously described. The low/reverse clutchsolenoid-actuated valve 636 is cycled or modulated (MOD) by commandsignals from the transmission controller 3010 to allow fluid to flowbetween the third 678c and fourth 678d lands of the solenoid switchvalve 610 to one end of the fourth land 674d of the LU switch valve 614to actuate or cycle it by fluid pressure, resulting in partial lock-upof the torque converter 110. Fluid also flows to one end of the fourthland 672d of the T/C control valve 612. This is because the fluid to oneend of the fourth land 672d moves the T/C control valve 614 to one endof its valve bore and the fluid flow configuration maintains the valve'sposition during the off period of the duty cycle, causing quick torquebuild-up by the lock-up clutch 186 and slow torque loss rate by lock-upclutch 186 (i.e. goes to unlock more slowly).

As illustrated in FIG. 5H, when the operating mode of the transmission100 is to be third gear, the manual valve 604 remains in the sameposition as first gear. Fluid flows from the pump assembly 200 to themanual valve 604. Fluid flows through the manual valve 604 between thefirst 676a and second 676b lands to the underdrive clutchsolenoid-actuated valve 630 which is normally applied and allows fluidflow to the underdrive clutch apply cavity 618 as previously described.Fluid from the manual valve 604 also flows to the overdrive clutchsolenoid-actuated valve 632 which is energized by the transmissioncontroller 3010 and moves to open the flow path to the overdrive clutchapply cavity 620 behind the first hydraulic piston 386 to apply theoverdrive clutch assembly 304.

Fluid from the manual valve 604 further flows to the third ball checkvalve 656 which is moved to close the flow path to the low/reverseclutch apply cavity 626. Fluid also flows to the low/reverse clutchsolenoid-actuated valve 636 which is normally vented and is preventedfrom flowing through the flow path to the solenoid switch valve 610.Fluid from the underdrive clutch solenoid-actuated valve 630 also flowsto the solenoid switch valve 610 between the fourth 678d and fifth 678elands and to both sides of plug 686 of the solenoid switch valve 610 aspreviously described. Fluid from the overdrive clutch solenoid-actuatedvalve 632 flows between land 670c and plug 688 and sleeve 690 of thepressure regulator valve 608. Since fluid pressurized plug 680 has thesame contact or pressure area as plug and sleeve 688, 690, these plugsare redundant. Hence, pressure area of third land 670c is the onlyactive area, moving the pressure regulator 608 and causing a new linepressure.

Fluid in the clutch apply cavities 626 and 624 of the low/reverse clutch310 and two/four shift clutch assemblies 308, respectively, is vented aspreviously described, resulting in these clutches not being engaged orapplied. The reverse clutch assembly 306 receives some fluid and isessentially vented as previously described. Fluid from the pump assembly200 also flows to the LU switch valve 614 as previously described. Fluidfrom the pump assembly 200 further flows to the two/four shift clutchsolenoid-actuated valve 634. However, this valve is energized by thetransmission controller 3010 and moves to block fluid flow as previouslydescribed.

As illustrated in FIG. 5I, when the partial lock-up feature is used inthird gear, the LU switch valve 614 is moved by fluid pressure toprevent fluid flow from the T/C control valve 612 from reaching thelock-up clutch assembly 186 as previously described. Thus, fluid flow isvented from the lock-up clutch assembly 186 of the torque converter 110at the LU switch valve 614. Fluid from the pump assembly 200 flowsthrough the LU switch valve 614 between the third 674c and fourth 674dlands to the torque converter 110, causing the lock-up piston 188 toengage the friction disc 199 resulting in lock-up of the torqueconverter 110. Further, fluid from the torque converter 110 flowsthrough the T/C control valve 612 past the cooler 616 and is used forlubrication. The low/reverse clutch solenoid-actuated valve 636 iscycled by command signals from the transmission controller 3010 to allowfluid flow from the manual valve 604 through the solenoid switch valve610 to one end of fourth land 674d of the LU switch valve 614 and fourthland 672d of the T/C control valve 612 to actuate or cycle these valvesfor partial lock-up of the torque converter 110 as previously described.

As illustrated in FIG. 5J, when the full lock-up feature is used inthird gear, the lock-up switch valve 614 is moved by fluid pressure toprevent fluid from the T/C control valve 612 from reaching the lock-upassembly 186 as previously described. The low/reverse clutchsolenoid-actuated valve 636 is energized by the transmission controller3010 and moves to allow full fluid flow from the manual valve 604through the solenoid switch valve 610 to one end of fourth land 674d ofthe LU switch valve 614 and fourth land 672d of the T/C control valve612 as previously described. In other words, the low/reverse clutchsolenoid-actuated valve 636 is not cycled, but energized fully for apredetermined time period, preventing the LU switch valve 614 from beingcycled and resulting in full lock-up of the torque converter 110.

As illustrated in FIG. 5K, when the operating mode of the transmission100 is to be fourth gear in the overdrive OD position, fluid flows fromthe pump assembly 200 to the manual valve 604. Fluid flows through themanual valve 604 between the first 676a and second 676b lands to thesecond ball check valve 654. The second ball check valve 654 is moved byfluid pressure to close one flow path to the underdrive clutch applycavity 618. Fluid flows from the manual valve 604 to the underdriveclutch solenoid-actuated valve 630 which is energized by thetransmission controller 3010 and moves to close the other flow path tothe underdrive clutch apply cavity 618. Fluid also flows from the manualvalve 604 to the overdrive clutch solenoid-actuated valve 632 which isenergized by the transmission controller 3010 and moves to open the flowpath to the overdrive clutch apply cavity 620. Fluid from the manualvalve 604 also flows to the low/reverse clutch solenoid-actuated valve636 which is normally vented, preventing fluid flow to the solenoidswitch valve 610. Fluid from the manual valve 604 further flows to thethird ball check valve 656 which is moved to close the flow path to thelow/reverse clutch apply cavity 626. Fluid from the pump assembly 200further flows to the two/four shift clutch solenoid-actuated valve 634which is normally applied and allows fluid flow through it to the manualvalve 604. Fluid flows between the third 676c and fourth 676d lands ofthe manual valve 604 to the two/four shift clutch apply cavity 624.

Fluid in the clutch apply cavities 626 and 618 of the low/reverse clutch310 and underdrive clutch 302 assemblies, respectively, is vented aspreviously described, resulting in these clutches not being engaged orapplied. The reverse clutch assembly 306 receives some fluid but isessentially vented as previously described. Fluid from the pump assembly200 also flows to the lock-up switch valve 614 and to the pressureregulator 608 as previously described.

As illustrated in FIG. 5L, when the full lock-up feature is used infourth gear, the LU switch valve 614 is moved by fluid pressure toprevent fluid flow from the T/C control valve 612 from reaching thelock-up clutch assembly 186. Thus, fluid flow is vented from the lock-upclutch assembly 186 of the torque converter 110 to the sump aspreviously described. The low/reverse clutch solenoid-actuated valve 648is energized by the transmission controller 3010 for a predeterminedtime period and moves to allow full fluid flow from the manual valve 604through the solenoid switch valve 610 to one end of the fourth land 674dof LU switch valve 614 and the fourth land 672d of the T/C controlcontrol valve 612 as previously described, resulting in full lock-up ofthe torque converter 110.

LIMP-HOME MODE PROTECTION

Since a limp-home mode is typically needed in the presence of a failure,it must be designed to have virtually absolute reliability. Accordingly,the transmission controller 3010 is designed with a master power relaywhich will only remain energized with full and proper controlleroperation, thus assuring the ability to achieve a power-Off state. Thesolenoid state in limp-home is "Off" or de-energized. Therefore, the Offor "normal" state of the solenoid-actuated valves 630, 632, 634, 636provide the needed clutch application. The solenoid-actuated valves 630,632, 634, 636 are ball-type valves (FIGS. 8 and 9) which functionwithout any dirt-sensitive close clearances and which will be effectiveeven with dirt on the valve seat. The manually actuated valve 604 is theonly component which must function to achieve second gear in OD, D or L,neutral in N, reverse in R and park in P.

Referring to FIG. 5F which illustrates the hydraulic schematic forsecond gear operation, fluid flows through the manual valve 604 betweenthe first 676a and second 676b lands and through the underdrive clutchsolenoid-actuated valve 630 which is normally applied, to the underdriveclutch apply cavity 618 as previously described. Fluid also flows fromthe manual valve 604 to the overdrive clutch solenoid-actuated valve 632which is normally vented and is prevented from flowing to the overdriveclutch apply cavity 618. Fluid from the manual valve 604 also flows tothe third ball check valve 656 which closes the flow path to thelow/reverse clutch apply cavity 626. The manual valve 604 further allowsfluid in the overdrive clutch 304, reverse clutch 306 and thelow/reverse clutch 308 assemblies to vent as previously described,resulting in these clutches not being engaged or applied. Fluid from thepump assembly 200 also flows through the two/four clutchsolenoid-actuated valve 634 which is normally applied to the manualvalve 604. Fluid then flows between the third 676c and fourth 676d landsof the manual valve 604 to the two/four shift clutch apply cavity 624 aspreviously described. Hence, second gear is achieved.

It is also important to note that the limp-home mode protection featureof the present invention is also designed to allow reverse gear to beused. The transmission 100 will operate in accordance with the hydraulicschematic of FIG. 5C in order to permit use of the transmission'sreverse gear. However, all of the solenoid-actuated valves will be intheir "normal" state.

It is further important to note that the limp-home mode protectionfeature of the prevent invention is also designed to allow park andneutral operating modes to be used. The transmission 100 will operate inaccordance with the hydraulic schematic of FIG. 5A except that all ofthe solenoid-actuated valves will be in their "normal" state.

DIRT-SHEDDING VALVES

In order to keep valves in a hydraulic system from sticking, it ispreferable to supply them only with clean or substantiallycontaminant-free fluid from the pump, taken in through a filter. The LUswitch valve 614 and the T/C control valve 612, however, are exposed tothe relatively dirty fluid exiting the torque converter 110 where thelock-up friction clutch 186 and the torque converter thrust washerscontribute dirt and other contaminants. In order to minimize the chanceof these valves 612, 614 from sticking due to this dirt, there is higherpressure fluid in the ports adjacent to a port in which dirty fluidflows. In other words, fluid flow containing substantially no foreignmatter or dirt is of a higher pressure than the fluid flow containing arelatively substantial amount of foreign matter or dirt in an adjacentport at a lower pressure. Thus, the pressure differential prevents thedirt from entering the close clearance between the lands of the valves612, 614 and the valve body 603 (See FIGS. 5A-L, 6 and 11A).

Additionally, in accordance with another aspect of the presentinvention, the major valves 610, 612 and 614 for controlling the flow ofhydraulic fluid through the system 600 have been advantageously designedto collect and subsequently shed or otherwise remove dirt and othercontaminants from these valves.

As illustrated in FIG. 11a, the solenoid switch valve 610 includes atleast one, preferably a plurality of axially spaced circumferentialgrooves 692 formed in its lands and plugs. The grooves 692 serve as ameans to collect dirt and other contaminants in the fluid. Similargrooves are also formed in the T/C control valve 612 and the LU switchvalve 614.

In operation, when the valve 610 passes a land 694 in the valve body603, the land 694 will push dirt collected on the valve into the groove692. Then, whenever the groove 692 passes a port 696, the flowing fluidthrough the port 696 flushes the dirt from the groove 692, therebykeeping dirt and other contaminants from inhibiting the operation of thevalves 610, 612 and 614.

VENT RESERVOIR

The vent reservoir 628 is placed in the hydraulic system 600 and acts asa means to reduce unwanted gasses or air intermittently trapped withinthe hydraulic passageways 602, etc. The vent reservoir 628 is disposedinside the manifold assembly 700, and is further illustrated in FIG. 8.The passageways 602 to the solenoid-actuated valves 630, 632, 634 and636 vent to a chamber inside the manifold assembly 700 forming the ventreservoir 628. The vent reservoir 628 maintains a fluid level above thevent port 727 of each solenoid-actuated valve 630, 632, 634, 636. Thevent reservoir 628 is elevated approximately three or four inches abovethe valve body 603. This, of course, maintains that same fluid level ineach clutch passageway 602 and thereby ensures rapid hydraulic responseof the overall fluid or hydraulic system 600 by eliminating accumulatedair in the hydraulic system 600 and eliminating the necessity of purgingthe hydraulic passages 602 of air as has been done in the past.Additionally, any trapped air is allowed to vent automatically to thevent reservoir 628.

SOLENOID SWITCH VALVE

The reciprocal fluid or solenoid switch valve 610 is a particularlyunique and advantageous feature of the present invention. It provideshydraulic protection against the simultaneous actuation of thelow/reverse clutch solenoid-actuated valve 636 and either the two/four634 or overdrive 632 clutch solenoid-actuated valves. The solenoidswitch valve 610 allows double use of low/reverse solenoid-actuatedvalve 636 to control fluid flow to the low/reverse clutch assembly 310and to the lock-up clutch assembly 186. The hydraulic protection featureis achieved by designing the valve 610 so that for a downshift to firstgear, a specific logic controlled sequence of solenoid commands from thetransmission controller 3010 is required to allow low/reverse clutchapplication after an upshift from first gear has occurred. Moreover, thevalve 610 has been designed so that a failure caused application ofeither the two/four shift 308 or overdrive 304 clutch assemblies, whilethe low/reverse clutch assembly 310 is applied, will simply vent thelow/reverse clutch assembly 310 and shift the transmission 100 to secondgear or third gear, respectively. Any control failure which mightattempt to apply the low/reverse clutch assembly 310 while in second,third or fourth gear is prevented from doing so by this valve 610. Applyfluid pressure from two/four 634 or overdrive 632 or underdrive 630solenoid-actuated valves can keep the valve 610 in the upshiftedposition (spool to the left in FIG. 5F) which precludes any low/reverseclutch assembly 310 application.

The logic sequence used during a downshift to first gear is FIRST, waitbriefly until the two/four or overdrive clutch pressure falls to lessthan 60% of the fluid line pressure (generated by the combination of thepressure regulator valve 608, pump assembly 200, and other systemfactors); SECOND, turn OFF the underdrive clutch solenoid-actuated valve630--this will downshift the valve 610 (move valve 610 to its positionin first gear as in FIG. 5E) without allowing slippage in the underdriveclutch 302 since the pressure used is from the solenoid end of a controlorifice U1 in the underdrive clutch passage (fluid from control orificeU1 to the solenoid-actuated valve 630 is vented at valve 630 while fluidbetween control orifice U1 and clutch apply cavity 618 is essentiallymaintained, resulting in a fluid pressure to keep the underdrive clutch302 from slipping); THIRD, wait briefly for valve motion to cease;FOURTH, turn ON low/reverse solenoid-actuated valve 636; and FIFTH, lookfor confirmation from low/reverse pressure switch 650; SIXTH, ifconfirmation is received, turn OFF low/reverse solenoid-actuated valve636 briefly to wait for valve actuation pressures to stabilize andSEVENTH, return to normal downshift logic. If low/reverse confirmationis not received, return logic to second gear.

Other features of the solenoid switch valve 610 are obtained. Firstly,by using differential areas on the valve 610 to move the valve 610instead of a spring, the valve 610 maintains the proper valve positionwith variations in fluid or line pressure. Secondly, line pressure isalways acting on one end of the valve 610 to put it into a position tocontrol fluid flow to the low/reverse clutch assembly 310. Thus, onstart-up, a high force is available to position the valve 610 properly.Additionally, high line pressure in the reverse R operating mode acts todislodge or free the valve 610 if stuck in a position to allow controlof the LU switch valve 614.

Thirdly, the fluid pressure top of the underdrive clutch assembly 302 tothe solenoid switch valve 610 is located on the solenoid side of thecontrol orifice U1 to provide for a rapid drop in the "latch pressure"without causing a significant loss of fluid pressure to the underdriveclutch assembly 302. This provides a means to allow the valve 610 tomove back to the low/reverse control position without affecting shiftquality.

Fourthly, it is significant that at least one of the three pressureswhich can keep the valve 610 in its upshifted position (LR vented and LUcontrolled) is essentially equal to line pressure during any shift whichmay occur, i.e. 2-3, 3-2, 3-4, 4-3, 2-4 or 4-2. This not only ensurescontinuous protection against failures, but also maintains theavailability of control of the lockup clutch 186 during shifts. Fluidpressure on underdrive clutch 302 keeps the valve 610 upshifted during2-3 or 3-2; pressure on the overdrive clutch 304 keeps the valve 610upshifted during the 3-4 or 4-3; pressure on the two-four shift clutch308 keeps the valve 610 upshifted during the 4-2 or 2-4.

As illustrated in FIGS. 5F through 5L, the solenoid switch valve 610remains in a valve position at one end of its valve bore in second,third or fourth gears, as well as during shifts between these gears.This valve position disconnects the low/reverse solenoid-actuated valve636 from the low/reverse clutch apply cavity 626 and connects valve 636to the LU switch valve 614, and vents the low/reverse clutch assembly310 as previously described.

The solenoid switch valve 610 eliminates the need for a fifthsolenoid-actuated valve for the lock-up mode which would add to the costand complexity of the system. This double duty operation is illustrated,for example, in FIGS. 5E and 5J.

Referring to FIG. 5E, the solenoid switch valve 610 is shown to be in afirst position to allow fluid flow from the manual valve 604 through thelow/reverse clutch solenoid-actuated valve 636 and between the second678b and third 678c lands of the solenoid switch valve 610 to thelow/reverse clutch apply cavity 626 as previously described. Asillustrated in FIG. 5J, the solenoid switch valve 610 is moved to asecond position during an upshift from first gear to allow fluid flowfrom the manual valve 604 through the low/reverse clutchsolenoid-actuated valve 636 and between the third 678c and fourth 678dlands of the solenoid switch valve 610 to one end 691 of the LU switchvalve 614 to control engagement of the lock-up clutch assembly 186 aspreviously described. Thus, the solenoid switch valve 610 has a firstposition to control fluid flow to the low/reverse clutch assembly 310and a second position to control fluid flow to the lock-up clutchassembly 186.

DIRECT-ACTING, NON-CLOSE CLEARANCE SOLENOID-ACTUATED VALVES

Advantageously, the present invention provides direct-acting, non-closeclearance solenoid-actuated valves, namely solenoid-actuated valves 630,632, 634 and 636. An example of a solenoid operated directional controlvalve is disclosed in U.S. Pat. No. 4,338,966, issued July 13, 1982 toSmith, which is hereby incorporated by reference. The solenoid-actuatedvalves 630, 632, 634 and 636 directly control fluid flow to theirrespective clutch assemblies. Since the solenoid-actuated valves 630,632, 634 and 636 have a non-close clearance design to be describedherein, dirt and other contaminants do not inhibit thesesolenoid-actuated valves from achieving either their normal orsolenoid-actuated position. Additionally, as previously described, thesesolenoid-actuated valves 630, 632, 634, 636 are designed to provide alimp-home mode of operation.

Referring to FIG. 7, a manifold assembly 700 is shown. The manifoldassembly 700 houses or contains the solenoid-actuated valves 630, 632,634 and 636. A cover member 702 is secured by suitable fastening means704, such as a screw and washer assembly, to a manifold housing 701. Acircuit and switch assembly 752 along with two perimeter seals 705 aresandwiched between the cover member 702 and manifold housing 701.

Referring to FIG. 8, the overdrive clutch solenoid-actuated valve 632,which is normally vented, is shown and is identical to the low/reverseclutch solenoid-actuated valve 636. The solenoid which actuates valve632 includes a stationary core member 706 having an outer cylindricalshape. A threaded portion 707 extends from one end of the core member706 and is threadably engageable with the manifold housing 701. Anelectrical coil assembly 710 is disposed coaxially around the coremember 706. A movable member or armature 712 is spaced axially from thecore member 706 to form a working air gap 714 therebetween. An L-shapedmagnetic shunt member 715 is secured between the core member 706 and themanifold housing 701. One edge 716 of the shunt member 715 contacts orabuts the armature 712 to allow the armature 712 to pivot or hinge aboutthat line while efficiently transmitting the magnetic flux through thearmature 712 and shunt member 715. A plurality of blades 717 areconnected one end of the electrical coil assembly 710 and extendoutwardly therefrom. The blades 717 are removably disposed incorresponding biased slots 718 in the circuit and switch assembly 752. Abowed or wave spring 719 is disposed between the shunt member 715 andthe coil assembly 710 to bias or cause the blades 717 of the electricalcoil assembly 710 to fully engage the slots 718 in the circuit andswitch assembly 752. This prevents the electrical contact surfacesbetween the blades 717 and slots 718 from moving or vibrating which maycause excessive wear of these contact surfaces. Additionally, inconjunction with a cylindrical offset portion 712a of the armature 712,this coil position causes the working air gap 714 to be offset towardthe center inside of the coil assembly 710, resulting in a moreefficient magnetic flow. Also, resistors 713 are connected to thecircuit and switch assembly 752 and will be described subsequently.

A nonmagnetic spacer 719a is disposed between the shunt member 715 andcore member 706. The outside diameter of the spacer 719a is larger thanthe diameter of the core member 706 to avoid magnetic bridging due tofine magnetic debris in the system. The spacer center is configured toretain on a corresponding undercut of the core member 706 and on aprojection 708 connected to threaded portion 707 to enhance handling andto prevent the projection 708 from contacting radially the shunt member715 through the corresponding hole in the shunt member 715.

The other end of the armature 712 has an adjustment screw 720 threadablyengaged and, in turn, capable of contacting the spherical end 722 of avalve plunger 724, so that the valve plunger 724 will reciprocate inresponse to appropriate magnetically induced actuations of the armature712.

The adjustment screw 720 is welded to armature 712 after factory settingis established to prevent further thread movement. The adjustment of thescrew 720 establishes the working air gap 714 (typically 0.05 to 0.20mm) with all parts in the actuated or energized position such that: fullforce is available at the valve seat; there is allowance for valve wear;noise of armature 712 striking core member 706 is avoided; small debrisin the working air gap 714 does not cause malfunction; and consistentpull-in and drop-out characteristics are maintained.

The valve plunger 724 is formed with a conical portion 725 which, whenthe solenoid is energized, is shown to be in sealing engagement with avalve insert 726, thereby closing a vent port 727 leading to the ventreservoir 628. The valve insert 726 is disposed in a passageway 728which communicates between an inlet or supply port 730 and a clutch orelement port 732 leading to a clutch apply cavity. Filters or screens731 and 733 are disposed in the supply port 730 and clutch port 732,respectively, to filter or trap large debris (such as machining chips)and prevent its distribution through the hydraulic system 600 where itcould cause malfunction. A movable ball 734 is disposed between alocalized, non-sealing travel stop 736 in the passageway 728 and a seat738 on the valve insert 726. The valve plunger 724 is coaxially disposedwithin a central passage 740 formed in the valve insert 726 whichcommunicates with the passageway 728, vent port 727 and the clutch port732. As shown in FIG. 8, the valve plunger 724 has a fluted centralportion 724a which supports valve plunger 724 concentrically in thecentral passage 740, yet permits fluid to flow readily through thecentral passage 740 around the valve plunger 724.

Conventionally, the transmission shift control valve member is typicallya spool type valve having lands and being reciprocal between lands of ahousing. The diametrical clearance between the lands of the conventionalvalve member and housing range from 0.0002 to 0.001 inches, resulting inpotential sticking or jamming by small debris. The present inventionutilizes a ball 734 in an oversized passageway 728 to allow an open flowpath around the ball 734 during actuation or operation. Hence, closeclearances are not required between the ball 734 and passageway 728. Infact, momentarily during the valve ball movement from one seat to theother, the present invention allows a burst of fluid flow from supplyport 730 to vent port 727 which flushes the passages.

Additionally, the circuit and switch assembly 752 includes an insulativecircuit housing 753 disposed between the cover member 702 and themanifold housing 701 (See FIGS. 7 and 8). A male plug member 754 isconnected to the circuit housing 753 for attachment to an externalsource of electrical power such as the transmission controller 3010.

In operation, the overdrive clutch solenoid-actuated valve 632 isnormally vented when not energized (i.e. no current flows through thewindings of the coil assembly 710). As a result, fluid enters the inletport 730 and flows through the passageway 728, causing the ball 734 tomove and engage the seat 738 of the valve insert 726. The ball 734 onits seat 738 blocks fluid flow from the inlet port 730, preventing fluidfrom entering clutch port 732. The displacement of the ball 734 movesthe valve plunger 724, causing the conical portion 725 to be disengagedor moved off the valve insert 726. As a result, fluid from the clutchport 732 flows through the central passage 740 along the plunger flutes724a and between the conical portion 725 and valve insert 726, ventingthrough vent port 727 to the vent reservoir 628. Hence, the overdriveclutch solenoid-actuated valve 632 and its related clutch assembly 304are normally vented.

When the overdrive clutch solenoid-actuated valve 632 is actuated, asshown in FIG. 8, current flows through the coil assembly 710 and createsa magnetic flux loop through the armature member 712, core member 706and shunt member 715. This magnetic flux causes a magnetic attractionbetween the armature 712, shunt member 715 and the core member 706. Thiscauses the armature 712 to move toward and contact the edge 716 of theshunt member 715 to reduce the working air gap 714, but not contact thecore member 706. The armature 712 pivots about the edge 716 of the shuntmember 715 and displaces the valve plunger 724, and in turn, displacesthe ball 734 off the seat 738 to allow fluid to flow from the inlet port730 past the ball 734 by way of passage 740 through the valve insert 726to the clutch port 732. Simultaneously, fluid also momentarily flows outvent port 727, producing a cleansing flush of conical portion 725. Themotion of armature 712 continues to drive valve plunger 724 untilconical portion 725 engages the surface of valve insert 726, therebyclosing vent port 727 and preventing continued fluid flow from clutchport 732 into vent reservoir 628 and thereby causing clutch pressure toincrease toward the level of inlet pressure. By appropriate time-cyclingof the current in coil 710, these valve ports will reciprocate rapidlyand provide effective control of the pressure in clutch port 732 at anydesired level between that of vent reservoir 628 and fluid flow frominlet port 730.

As partially illustrated in FIG. 9, the underdrive clutch 630 andtwo/four shift clutch 634 solenoid-actuated valves are normally appliedwhen not energized or no current flows through the windings of the coilassembly 710. Prime numerals are used for parts similar to the overdriveclutch solenoid-actuated valve 632 of FIG. 8. As a result, fluid entersthe inlet or supply port 730' and flows in the passageway 728', causingthe ball 734' to move and engage its seat 738' of the two piece valveinsert 726'. When the ball 734' is on or engaging the seat 738', a smallgap 739 exists between the ball 734' and another ball seat 737. As aresult, fluid flows in the gap 739 past the ball 734' and to the clutchport 732'. By engaging seat 738', the ball 734' prevents fluid flow fromexiting clutch port 732' via passage 740' and into the vent reservoir628. Hence, the solenoid-actuated valves 630 and 634 and their relatedtransmission clutch assemblies 302 and 308 are normally applied.

When the underdrive clutch solenoid-actuated valve 630 is actuated, thearmature 712 pivots and displaces the valve plunger 724', and in turn,displaces the ball 734' to engage seat 737. As a result, fluid flow fromthe supply port 730' is blocked by the ball 734' and is prevented fromflowing to the clutch port 732'. Fluid flow from the clutch port 732' isallowed to flow between the ball 734' and seat 738' and through centralpassage 740', venting through vent port 727' to the vent reservoir 628.As with the normally vented valves, clutch pressure may be regulated bytime-cycling the valve.

As illustrated in FIG. 9A, the present invention provides a means forreducing noise resulting from solenoid valve action. A spool 742 havinga generally cylindrical shape is disposed in the passageway 728. Thespool 742 can slide in the passageway 728. The spool 742 has an axiallyprojecting portion 744 extending into the central passage 740 of thevalve seat 726. The projecting portion 744 contacts the ball 734. Thespool 742 includes a chamber 745 and an aperture 746 extending axiallythrough the projecting portion 744, both of which allow fluid flowthrough the spool 742. A spring 747 is disposed within the chamber 745and biases or lightly loads the spool 742 toward the ball 734. In otherwords, the spring 747 biases the projecting portion 744 into contactwith the ball 734 so that the ball 734 contacts its seat 738. One end ofthe aperture 746 is closed by the ball 734 during pull-in or energizingof the coil assembly 710. During de-energization of the coil assembly710 (i.e. during drop-out), the ball 734 will return freely, opening theaperture 746 and allowing the chamber 745 to refill rapidly so that thenext pull-in can be cushioned.

The spool 742 also includes a first or supply end land 748 at one endwhich is slightly smaller in diameter than the passageway 728. Land 748allows only gradual flow of fluid out of a trapped cavity between land748 and the manifold housing 701 in passageway 728, thereby slowingpull-in velocity and reducing impact noise. The spool 742 furtherincludes a second or element end land 749 at the other end which isfluted for free flow of fluid.

In operation, during pull-in, the ball 734 moves axially, resulting inaxial movement of the spool 742. Land 748 allows only gradual flow offluid past it out of the trapped cavity between land 748 and themanifold housing 701 in the passageway 728. This gradual flow slows thepull-in velocity of the ball 734 and related valve plunger 724 (SeeFIGS. 8 and 9), reducing impact noise with the valve seat 726.

During drop-out, the ball 734 returns freely allowing the chamber 745 torefill rapidly so that the next pull-in can be cushioned. Also, spring747 will return the spool 742 so that the projecting portion 744 onceagain contacts ball 734 to rest the ball 734 on its seat 738. The spool742 may be used with both normally applied and normally ventedsolenoid-actuated valves.

Referring to FIG. 10, a pressure sensor or switch assembly 650 is shownand is similar to pressure switches 646 and 648 of FIGS. 5A-5L. Thepressure switch assembly 750 includes a circuit contact or pad 755communicates through a bore 756 formed in the circuit housing 753. Aretainer 758 secures a flexible rubber diaphragm 760 between themanifold housing 701 and the cylindrical wall of the circuit housing 753forming the bore 756. A contact cup 762 is disposed in the bore 756between the diaphragm 760 and cover member 702. A spring 764 is disposedbetween the contact cup 762 and cover member 702.

The diaphragm 760 is compressed between the circuit housing 753 and theretainer 758 to prevent excessive fluid pressure leakage whilecompensating for differences in dimensional stack-up. This compression,in turn, loads the face of the retainer 758 against the manifold housing701 such that an assured, highly restrictive leak path is intentionallyestablished to vent air from the hydraulic circuit to assure fast switchresponse (undamped) to solenoid action while allowing minimal fluidflow.

Additionally, the contact cup 762 has a relatively large diametricalclearance inside of the bore 756 and a large contact gap (long stroke)consistent with maintaining a system which is highly tolerant of dirtand debris. The contact side of the contact cup 762 is common with thevent reservoir 628 to avoid hydraulic damping (allowing fast response),yet protects the circuit contacts 755 from corrosion or electricalerosion (i.e. contacts remain covered by fluid).

In operation, fluid enters through apertures (not shown) in the retainer758 from the manifold housing 701 and displaces or deflects thediaphragm 760. The diaphragm 760, in turn, displaces the contact cup762, causing the contact cup 762 to contact the circuit contact 755completing a circuit through the cup 762, spring 764 and cover member702 which grounds circuit contact 755 to indicate the presence ofpressure to the transmission controller 3010. When the fluid pressure isremoved, the spring 764 returns the contact cup 762 out of contact withthe circuit contact 755, opening the circuit and indicating an absenceof pressure to the transmission controller 3010.

REVERSE LOGIC-DUMP & REAPPLY

Current state of the art automotive transmissions vent all frictionelements in the neutral position N of the shift lever. This means thatall elements needed to provide motion must be filled when selectingforward or reverse gears.

The present invention keeps the low/reverse clutch apply cavity 626filled under most conditions in neutral, thus only one clutch applycavity needs to be filled to provide either first gear or reverse gear.This provides for faster shifting under "rocking" conditions. For theshift from neutral to first gear, the underdrive clutch 302 is applied;for the shift from neutral to reverse gear, the reverse clutch 306 isapplied.

In order to obtain a couple unique advantages, however, the shift fromneutral to reverse gear is not performed by simply applying the reverseclutch 306. The "fully-applied-in-Neutral" low/Reverse clutch 310 isvented while the apply cavity 622 of the reverse clutch 306 is filling(the hydraulic circuit and controlling logic are designed so that thelow/reverse clutch torque is essentially zero before the reverse clutch306 can apply). The application of the reverse clutch 306, then, simplyengages or couples the gear assembly 500 to the input shaft 176, but noreaction element is applied to provide reverse drive. The reverse clutchapplication, therefore, does not need to be made in a controlled mannersince it does not effect the shift quality (i.e. no significant changein transmission output torque occurs during its application). Since thisis the only shift which uses the reverse clutch 306, this means that thereverse clutch 306 can simply be applied by the manual valve 604,thereby saving the cost and complexity of an additionalsolenoid-actuated valve. Moreover, the reverse clutch application doesnot involve significant energy since it only accelerates gearsetinertia; it, therefore, does not require a large number of clutch discsfor energy dissipation. These advantages justify the logic complexityinvolved in the low/reverse "dump and reapply" sequence.

Accordingly, the present invention provides a method for applying thereverse clutch 306. In order to achieve good shift quality, the controlmethodology must vent the low/reverse clutch apply cavity 626 down to afill level before the reverse clutch 306 applies. In other words, therapid dump and reapply feature is used to get the low/reverse clutch 310off rapidly before the reverse clutch 306 can apply. This preventsexcessive wear of the reverse clutch 306.

As illustrated in FIG. 5A, the low/reverse clutch apply cavity 626 iffilled, resulting in the low/reverse clutch assembly 310 being applied.The first ball check valve 652 has its ball seated on one side toprevent fluid from the low/reverse clutch apply cavity 626 venting intothe reverse circuit.

When the manual valve 604 is shifted to reverse R, the pressure of thefluid in the low/reverse clutch apply cavity 626 does not initiallyallow the ball of the first ball check valve 652 to move, therebymaintaining its seated position. This allows direct and rapid venting ofthe fluid in the low/reverse clutch apply cavity 626 past the third ballcheck valve 656 and through the manual valve 604 to the sump.Simultaneously, the low/reverse solenoid-actuated valve 636 is turnedoff to prevent fluid flow to the low/reverse clutch apply cavity 626.Since the manual valve 604 is shifted to reverse R, the reverse clutchapply cavity 622 is filling rapidly and applying quickly because thereis no accumulator or control logic for the reverse clutch 306.

During this time period, the two/four clutch solenoid-actuated valve 634is energized to prevent fluid pressure build-up through the reversecircuit. After a predetermined time period from the beginning of theshift to reverse, the transmission controller 3010 looks for a signalfrom the low/reverse pressure switch 650, indicating that the fluidpressure in the low/reverse clutch apply cavity 626 has dropped to afairly safe level. As soon as the signal from the low/reverse pressureswitch 650 is detected, an additional predetermined time period of 0.19seconds is added to vent the low/reverse clutch apply cavity 626. Thetwo/four clutch solenoid-actuated valve 634 is then turned off (i.e.de-energized) under duty cycle control to allow fluid flow in thereverse circuit. This fluid flow reseats the ball of first ball checkvalve 652 on its other seat, limiting the remaining amount of venting,and fills the low/reverse clutch apply cavity 626 to reapply thelow/reverse clutch 310. This methodology is represented by curves ortraces on a shift tape graph or recording for a shift from neutral toreverse gear as illustrated in FIG. 24L.

T/C CONTROL VALVE

Referring to FIG. 5A, the T/C control valve 612 is used to regulatetorque converter pressure (i.e. provide various pressures) and improvelock-up control. Generally, normal line pressure from the pressureregulator 608 is used to feed the torque converter 110., resulting inonly one pressure level.

As illustrated in FIGS. 5E and 5F, in first and second gear,respectively, the T/C control valve 612 regulates inlet fluid pressureto the torque converter 110 as determined by the area between lands 672cand 672d and spring 664. At this valve position, the torque converteroutlet flow to the cooler 616 is unrestricted.

Referring to FIG. 5C, in reverse gear, a passageway 602d to the T/Ccontrol valve 612 is not pressurized. The T/C control valve 612regulates the inlet fluid pressure to the torque converter in a similarmanner to first or second gear except that its range of authority isincreased (i.e. useful range of solenoid duty cycle of about 40% to 95%as opposed to 60% to 90%) by virtue of passageway 602d being vented.

Referring to FIGS. 5H and 5K, in third and fourth gear, the linepressure to the T/C control valve 612 is low enough for the spring 664to move the T/C control valve 612 to allow full unrestricted flow to thetorque converter 110. The pressure of the fluid to the torque converter110 is essentially the same as the line pressure minus typical pipelosses, etc.

Referring to FIG. 5I, in partial lock-up, the low/reversesolenoid-actuated valve 636 is cycled by the transmission controller3010. This pressurizes the end of fourth land 672d of the T/C controlvalve 612 enough to keep it effectively in the position shown. In thisposition, both the torque converter inlet and outlet flow arerestricted, which reduces the lock-up clutch rate of torque reductionduring the solenoid-actuated valve 636 off period as previouslydescribed. This extends the lock-up clutch control range (i.e. usefulrange of solenoid duty cycle) down to lower duty cycles ofsolenoid-actuated valve 636.

CAM CONTROLLED MANUAL VALVE

The present invention provides a cam controlled manual valve 604.Referring to FIG. 11B, a pin or shaft member 770 is connected bysuitable means to one end of the manual valve 604. The shaft member 770is disposed in a slot or cam groove 772 of the manual lever 578 which isconnected to the manual shaft 591, as illustrated in FIG. 4B. The shaftmember 770 follows the irregular path of the cam groove 772 to move orreciprocate the manual valve 604 axially in its bore of the valve body603.

In operation, the operator or driver moves the manual shaft 591 to thedesired gear or operating mode position, i.e. PRNODDL. This causes themanual lever 578 to rotate. As the manual lever 578 is rotated, theengagement of the cam groove 772 and shaft member 770 acts as a cammeans, causing the manual valve 604 to be displaced or shifted in itsbore of the valve body 603 to connect the proper ports between the landsthereof to allow fluid flow to the proper clutch apply cavities to movethe corresponding fluid actuating device or clutch apply piston.

Accordingly, the present invention allows additional PRNODDL positionswithout changing either the manual valve 604 or valve body 603. This isaccomplished by the irregular path of the cam groove 772. The cam groove772 defines a park position at one end for a park operating mode of thetransmission 100 and an installation position at the other end forinstalling the park locking mechanism 560. The cam groove 772 furtherdefines a reverse, neutral, overdrive, drive and low position for theircorresponding operating mode, respectively. Also, the present inventionreduces the travel and length of the manual valve 604. The presentinvention further permits solenoid switching (described below) whilemaintaining a balanced valve, i.e. no sine loads from the fluid flow.

MANUAL VALVE SOLENOID SWITCHING

As illustrated in FIG. 11B, the manual valve 604 is shown. The manualvalve 604 has lands 676a, 676b, 676c, 676d located such that it is ableto switch the fluid flow between the two/four shift clutchsolenoid-actuated valve 634 and the low/reverse clutch solenoid-actuatedvalve 636. Referring to FIG. 5C, in reverse gear, fluid flows throughpassageway 602a to the manual valve 604. The manual valve 604 allowsfluid to flow between lands 676a and 676b and through passageway 602b tothe reverse clutch apply cavity 622. Fluid also flows from the pumpassembly 200 through the two/four shift clutch solenoid-actuated valve634 to the low/reverse clutch apply cavity 626.

Referring to FIG. 5E, in low gear, i.e. first gear, fluid flows throughpassageway 602a to the manual valve 604. The manual valve 604 is shiftedor moved to allow fluid to flow through the manual valve 604 betweenlands 676a and 676b and through passageway 602c and through thelow/reverse clutch solenoid-actuated valve 636 to the low/reverse clutchapply cavity 626. Thus, the position of the manual valve 604 is such toswitch fluid flow between solenoid-actuated valves 634 and 636 to allowfluid flow to the low/reverse clutch apply cavity 626 in first andreverse gears.

TRANSMISSION CONTROL METHOD

Referring to FIG. 12, the logic or methodology of the transmissioncontroller 3010 is shown at 800. When the key of the vehicle is turnedon, power-up of the transmission controller 3010 occurs in bubble 802.Next, the transmission controller 3010 performs or enters a sevenmillisecond (7 ms.) main program or control loop. At the beginning ofthe main control loop, the methodology advances to block 804 calledshift select to "orchestrate" various methods used to determine theoperating mode or gear, i.e. first gear, the transmission 100 ispresently in and which gear the transmission 100 should be in next, andcomparing the two to each other to determine if a shift is required. Themethodology advances to bubble 806 to calculate the speed andacceleration of the turbine 128, output gear 534 and engine crankshaft114. The transmission controller 3010 receives input data from theturbine speed sensor 320 (turbine speed N_(t)), output speed sensor 546(output speed N_(o)) and engine speed sensor (not shown) (engine speedN_(e)) in circle 808. In bubble 806, the engine speed N_(e), turbinespeed N_(t) and output speed N_(o) are calculated from the input data.The methodology advances to bubble 810 called the shift schedule to bedescribed under section heading "SHIFT SCHEDULE METHOD". The shiftschedule bubble 810 reads or determines the shift lever position 606,PRNODDL, of the manual lever 578 by contact switch sensors (NS₁, NS₂)(See FIG. 4B) in circle 812. The shift schedule bubble 810 alsodetermines the throttle angle THRT ANGLE of the engine, to be describedunder section heading "THROTTLE ANGLE COMPUTATION AND FAILUREDETECTION", by an input of a potentiometer (not shown) connected to thethrottle (not shown) in circle 814. The shift schedule bubble 810further determines the engine temperature, to be described under sectionheading "PRESSURE SWITCH TEST AND TRANSMISSION TEMPERATURE DETERMINATIONMETHOD" in circle 816. The shift schedule bubble 810 uses the data itemssuch as output speed N_(o) in circle 815 (generated by bubble 806),PRNODDL (generated by circle 812) and throttle angle (generated bycircle 814) to determine the appropriate gear the transmission 100should be placed.

The methodology advances to bubble 818 which outputs the appropriatecommand signals to the solenoid-actuated valves 630, 632, 634 and 636and properly energizes or de-energizes them based on which gear thetransmission 100 is in, as determined by circle 812. The methodologyadvances to bubble 820 to execute diagnostic or monitoring routines. Indiagonstic bubble 820, the transmission controller 3010 determines ifthe proper pressure switches 646, 648 and 650, previously described, arepressurized by either looking for signals from a specific pressureswitch combination for the present in-gear condition of the transmission100 or from a specific pressure switch to a non-controlling clutchduring a pressure switch test to be described. The transmissioncontroller 3010 also determines if the wires in the control system arenot shorted or open by looking for a flyback voltage or EMF spike duringa solenoid continuity test to be described under section "SOLENOIDCONTINUITY TEST METHOD". The methodology then advances to diamond 822and determines whether a failure has occurred. If a failure hasoccurred, the methodology advances to block 824 in which thetransmission controller 3010 de-energizes the solenoid-actuated valves630, 632, 634 and 636 which assume their normal positions to allow thetransmission 100 to operate in second gear in the drive mode, i.e.limp-home mode previously described. If a failure has not occurred, themethodology advances to the shift select block 804. Based on thecalculated speeds and shift schedule output (SSOUTP), the methodologydetermines if a shift is required. This process is done every 7 ms.

Since the shift select block 804 compares the gear the transmission 100is presently in, to the SSOUTP, the methodology advances to diamond 826and determines if a shift or gear change is required. If a shift isrequired, the methodology advances to block 828 called the shift logicto be described herein. Otherwise, if a shift is not required, themethodology advances to diamond 830 and looks at the lock-up schedules,i.e. a plot of THRT ANGLE verses N_(t), etc., to determine if lock-up ofthe torque converter 110 is required. If lock-up is not required, themethodology returns to the beginning of the shift select block 804 againfor another 7 ms. loop. Otherwise, if lock-up is required, themethodology advances to diamond 832 and determines if the torqueconverter 110 is presently locked-up by looking for a flag that haspreviously been set during full lock-up of the torque converter 110. Ifthe torque converter 110 is presently locked-up, the methodology returnsto the shift select block 804. Otherwise, the methodology advances toblock 834 called partial lock-up logic or methodology, to be describedunder section heading "TORQUE CONVERTER LOCK-UP METHOD", for the torqueconverter 110.

If a shift or gear change is needed or required, the shift logic block828 uses one of twelve unique shift programs or routines. The shiftroutines are 1-2, 2-3, 2-4, 3-4 (upshifs); 4-3, 4-2, 3-2, 3-3, 2-1,(downshifts); and N-l, R-N, N-R (garage shifts) to be described herein.The shift logic block 828 has to identify the proper shift logicroutine, and then execute it. The shift logic block 828 controls thesolenoid-actuated valves 630, 632, 634 and 636 to shift the transmission100 from its present gear to the next gear in a smooth manner.

After the shift logic block 828, the methodology advances to diamond 836and determines if lock-up of the torque converter 110 is required aspreviously described. If lock-up is required, the methodology advancesto diamond 838 and determines whether the torque converter 110 isalready locked-up as previously described. If the torque converter 110is not already locked-up, the transmission controller 3010 executes thepartial lock-up block 834, to be described herein.

The partial lock-up block 834 is used to reduce slip of the torqueconverter 110. Slip equals N_(e) minus N_(t). The partial lock-up block834 instructs or causes the transmission 100 to fully lock, partiallylock or fully unlock the torque converter 110. If unlock is desired, thetransmission controller 3010 will hold the solenoid-actuated valve 636in the de-energized or normally vented mode to move the LU switch valve614 and allow fluid pressure to disengage the lock-up clutch 186. Ifpartial lock is desired, the transmission controller 3010 will reduceslip to a low or predetermined desired value, but not completelyeliminate it. The transmission controller 3010 calculates the slip byN_(e) minus N_(t) based on the input from the sensors previouslydescribed. The transmission controller 3010 compares this to apredetermined desired value of slip, e.g. 60 r.p.m., and thus,determines if the torque converter 110 is slipping too much or toolittle. If too much slip occurs, the transmission controller 3010 willincrease the duty cycle ("ON" time) of the low/reverse clutchsolenoid-actuated valve 636 and the LU switch valve 614, which willincrease the pressure differential across the lock-up clutch assembly186 and thus, decrease the slip. This technique is called "pulse-widthmodulation".

If full lock-up is desired, the transmission controller 3010 willgradually increase the fluid pressure to the lock-up clutch 186, addingmore "ON" cycle time to the solenoid-actuated valve 636 therebyincreasing the "ON" cycle time at the LU switch valve 614 until maximum,resulting in zero slip.

Returning to diamond 836, if the transmission controller 3010 determinesthat lock-up of the torque converter 110 is not required, themethodology advances to bubble 840 to execute diagnostic or monitoringroutines as previously described. Similarly, if the transmissioncontroller 3010 determines that the torque converter 110 is alreadylocked-up in diamond 838, the methodology advances to bubble 840 toexecute diagnostic or monitoring routines as previously described.Further, once the partial lock-up block 834 is completed, themethodology advances to bubble 840 to execute diagnostic or monitoringroutines as previously described.

From diagnostic bubble 840, the methodology advances to diamond 842 anddetermines whether a failure has occurred as previously described. If afailure has occurred, the methodology advances to block 844 and causesthe transmission 100 to default to or operate in second gear. Otherwise,if no failure occurs in diamond 842, the methodology advances to diamond846 and determines if the time period for the diagnostic loop hasexpired by any suitable method such as looking at a counter. If the timehas not expired, the methodology advances to bubble 840 to execute thediagnostic routines again until the time period has expired. If the timeperiod has expired, the methodology advances to bubble 848 to calculatespeeds N_(e), N_(t) and N_(o) as previously described. The methodologythen advances to bubble 850 to perform another shift schedule aspreviously described using PRNODDL circle 852, output speed N_(o) circle855, THRT ANGLE circle 854, and engine temperature circle 856.

To perform the shift in a smooth manner, the transmission controller3010 slips the clutches of the multi-clutch assembly 300. Thetransmission controller 3010 has to control the pressure on applyingclutches and releasing clutches in an orchestrated manner. To do this,the methodology advances from the shift schedule bubble 850 to bubble858 and determines the appropriate rate of acceleration, called the"desired acceleration" (alpha_(desired) or α*) to control the turbine128. The desired acceleration may be predetermined by an equation,point/slope interpolation or any other suitable method. The methodologyadvances to bubble 860 and calculates the present acceleration(alpha_(t) or α_(t)) of the turbine 128 based on turbine speed N_(t)which tells the transmission controller 3010 how quickly the shift ishappening. The transmission controller 3010 indirectly compares thevalue of desired acceleration with the calculated acceleration. This maybe accomplished by placing the above values into an equation to decidethe duty cycle for proportional control to be described. The methodologyadvances to bubble 862 to output the appropriate command signals toeither actuate and/or deactuate (turn logically either "ON" or "OFF")the solenoid-actuated valves 630, 632, 634 and 636 for the engaging(apply) or disengaging (release) of the clutches.

For upshifts, if the turbine 128 is decelerating too fast, thetransmission controller 3010 reduces the pressure on the applying clutchby either actuating and/or deactuating the solenoid-actuated valves 630,632, 634 and 636 in bubble 862. For downshifts, if the turbine 128 isaccelerating too rapidly, the transmission controller 3010 increases thepressure on the applying clutch by either actuating and/or deactuatingthe solenoid-actuated valves 630, 632, 634 and 636 in bubble 862. If theturbine assembly 128 is accelerating at the desired acceleration level,the solenoid-actuated valves 630, 632, 634 and 636 are either actuatedand/or deactuated to obtain the shift or gear change. At the end of 7ms. loop, the methodology advances to diamond 864. The transmissioncontroller 3010 tallies the ratios of N_(t) to N_(o) again to determineif the shift or gear change is complete. If N_(o) and N_(t) are atproper values, i.e. ratio×N_(o) =N_(t) for a predetermined time periodwhich is different for each shift, the transmission controller 3010determines that the shift or gear change is complete. The methodologyreturns to the beginning of the control loop to the shift select block804. If the shift or gear change is not complete, the methodologyreturns to the shift logic block 828 to repeat the method as previouslydescribed.

SHIFT SELECTION METHOD

The shift "select" routine or method in block 804 of FIG. 12 falls inthe main loop immediately after system start-up in bubble 802 of FIG.12. The shift schedule routine of bubble 810 is called before shiftselection analysis is performed. All other key variables such as outputspeed N_(o), turbine speed N_(t), acceleration, etc. are also updatedprior to shift selection analysis. The shift schedule routine of bubble810 determines the appropriate gear the transmission 100 of the vehicleshould be placed in (See FIG. 13B) as described subsequently herein.This information is conveyed by setting the bits of "shift scheduleoutput" (SSOUTP). The shift selection block 804 compares the gearrelated bits of the in-gear code (IGCODE) as defined by circle 812 andSSOUTP. If they are equal, no shift is required. In this case, themethodology will decode what gear the transmission 100 is in and willrevalidate the proper "clutch" and "solenoid" states (i.e. eitherlogically "ON" or "OFF") of the valves 630, 632, 634 and 636 (FIGS.5A-L).

The shift selection method (FIG. 13B) has enormous complexity. In orderto minimize the size of the method to a manageable level and to deriveRAM and ROM efficacy, a technique using a shift "control table" isemployed. Each row of the shift control table has four bytes. The shiftcontrol table format is defined as follows:

    ______________________________________                                                          SHCODE IF     COMPLEMENT                                    MASK   IGCODE     IGCODE TRUE   SHCODE                                        ______________________________________                                        (1)    (2)        (3)           (4)                                           ______________________________________                                    

The SHCODE is the "shift code", i.e. from first to second gear. IGCODEis the in-gear code, i.e. present operating gear of the transmission100. MASK is the eight bit binary code for the result of a logicaloperation.

As illustrated in FIG. 13A, the shift select block 804 is generallyshown for a shift selection while the transmission 100 is operating "ingear", i.e. the transmission 100 is presently in first gear for example.After power-up in bubble 802 of FIG. 12, the methodology enters theshift select through bubble 866. The methodology advances to block 868and points to the beginning or start of the shift control table (firstrow), previously described, which is stored in memory. The methodologyadvances to block 870 and prepares a "select mask" (M) from which theIGCODE and SSOUTP are "logically AND-ed". The methodology advances toblock 872 and compares mask (M) with the first byte in the shift controltable row. The methodology advances to diamond 874 and determineswhether a matching row was found. If a matching row was found, themethodology advances to block 876 and points to the next row in theshift control table. The methodology then loops back to diamond 874previously described.

If a matching row was found at diamond 874, the methodology advances todiamond 876 and determines whether the present IGCODE equals the secondbyte of the shift control table row. If the present IGCODE equals thesecond byte, the methodology advances to block 878 and picks the thirdbyte containing the shift to be performed, i.e. first to second gear. Ifthe present IGCODE does not equal the second byte, the methodologyadvances to block 880 and picks the fourth byte containing the shift tobe performed. The methodology advances from blocks 878 and 880 to bubble882. At bubble 882, the methodology returns or goes to top of shift inshift logic block 828 of FIG. 12 to perform the shift just selected. Theshift select block 804 is shown schematically in FIG. 13B.

If the present shift is to be abandoned for a new shift, i.e. a shiftselection while the transmission 100 is presently performing a shift, aselection process called "change-mind" analysis is used as illustratedin FIG. 13C. During the shift loop, the methodology enters thechange-mind portion of the shift selection block 804 through bubble 884.The methodology then advances to diamond 886 and determines whether anew shift schedule is different from the present shift schedule bylooking at the shift schedule output (SSOUTP) which may be a codedregister. If not, the methodology advances to bubble 888 and determinesthat change-mind analysis is not allowed and continues the presentshift. If the new shift schedule (SSOUTP) is different from the presentshift schedule, the methodology advances to block 890 and vectors to theproper change-mind processing point based on a change mind table storedin memory which is similar to the shift control table. In other words,the methodology uses a vector table oriented method for analysis of each"present shift" and jumps to the proper process point. The methodologythen advances to block 892 and performs checks using key variables (i.e.speeds, throttle angle, speed ratios, SSOUTP, IGCODE, etc.) at itsappropriate processing point. The methodology advances to diamond 894and determines whether change-mind conditions are valid by the oldSSOUTP not matching the new or recent SSOUTP. If the conditions are notvalid, the methodology advances to bubble 888 previously described tocontinue the present shift. If the change-mind conditions are valid, themethodology advances to bubble 896 and aborts the present shift andselects the new shift from the processing point.

SHIFT SCHEDULE METHOD

The shift schedule method determines the appropriate gear in which thetransmission 100 should be placed. The shift schedule method firstdetermines the present gear of the transmission 100 by the shift leverposition 606 of the manual lever 578 in circle 812 of FIG. 12. Based onthe shift lever position 606, the shift schedule method determines theappropriate gear in which the transmission 100 should be placed.

Referring to FIG. 14A, the bubble 810 of FIG. 12 for the shift schedulemethod is shown. The methodology enters from the shift select block 804through bubble 900 and advances to diamond 902. At diamond 902, themethodology determines whether the shift lever position (SLP) 606 of themanual lever 578 is park P or neutral N by reading a coded signal fromthe sensors NS₁ and NS₂ (FIG. 4B) to be described. If SLP 606 is park orneutral, the methodology advances to block 904 and sets the new output(SSOUTP) of the shift schedule (SS) to neutral. The methodology thenreturns or exits through bubble 906.

At diamond 902, if SLP 606 is not park or neutral, the methodologyadvances to diamond 908 and determines whether SLP 606 is reverse R bythe signal from the sensors NS₁ and NS₂. If SLP 606 is reverse, themethodology then advances to block 910 and sets shift schedule toreverse. The methodology then returns or exits through bubble 906.

At diamond 908, if SLP 606 is not reverse, the methodology advances toblock 912 concludes or determines that SLP 606 is equal to overdrive OD,drive D or low L. The methodology then advances to block 914 and selectstwo adjacent lines based on the present shift schedule and the shiftschedule graphs shown in FIGS. 14B through 14D for a SLP 606 ofoverdrive OD, drive D or low L. The methodology advances to block 916and scans these lines using a technique called "point slope" (PSLOPE),to be described under section heading "PSLOPE METHOD" (FIGS. 15A and15B) which is a linear interpolation technique (N_(o) on X-axis andthrottle angle on Y-axis). The methodology advances to diamond 918 anddetermines whether there is a new shift schedule to a coastdown shift,i.e. second to first gear from the SSOUTP (for a downshift) and throttleangle (for coast versus kick). If there is a new shift schedule to acoastdown shift, the methodology advances to block 920 and checks thegear ratios of the gear assembly 500 by performing speed calculations toavoid a "shock" from a power-plant reversal situation. A power-plantreversal situation or condition exists when the wheels of the vehicledrive the engine through the transmission during deceleration ratherthan the engine driving the transmission, in turn, driving the wheels.The methodology advances to diamond 922 and determines whether apower-plant reversal situation or condition exists. If a power-plantreversal condition exists, the methodology advances to block 924 anddoes not change the shift schedule. The methodology returns or exitsthrough bubble 926.

At diamond 918, if there is not a new shift schedule to a coastdownshift, the methodology advances to block 928. Also, if a power-plantreversal condition does not exist at diamond 922, the methodologyadvances to block 928. At block 928, the methodology allows for a newshift schedule. The methodology then advances to block 930 and checksfor diagnostic situations or conditions as previously described inconjunction with FIG. 12. The methodology advances to diamond 932 anddetermines whether a diagnostic situation or condition exists. If adiagnostic condition does not exist, the methodology advances to block934 and allows the shift schedule to proceed or be changed to the newshift schedule. If the diagnostic condition does exist, the methodologyadvances to block 936 and does not change the shift schedule. Themethodology advances from blocks 934 and 936 to bubble 938 and exits orreturns.

PSLOPE METHOD

Referring to FIGS. 15A and 15B, the "point slope" (PSLOPE) routine ofblock 916 of FIG. 14A is shown. The PSLOPE method determines thethrottle angle given output speed N_(o) by scanning the shift lines inFIGS. 14B through 14D stored as a table in the memory of thetransmission controller 3010. At the start of the PSLOPE routine inbubble 1000 of FIG. 15A, the methodology advances to block 1002 andtemporarily stores the value for X in the memory of the transmissioncontroller 3010. The methodology then advances to diamond 1004 anddetermines whether X is less than or equal to X_(o) (FIG. 15B) which isa point on the shift line. If X is less than or equal to X_(o), themethodology advances to block 1006 and gets or obtains the value forY_(o) and returns or exits through bubble 1008. If X is greater thanX_(o), the methodology advances to diamond 1010 and determines whether Xis less than X_(R). If X is less than X_(R), the methodology advances toblock 1012 and computes the slope between the points X_(R) and X_(R-1).The methodology then advances to block 1014 and computes Y based onY_(R) plus slope. The methodology then returns or exits through bubble1016.

At diamond 1010, if X is not less than X_(R), the methodology advancesto diamond 1018 and determines whether the method is at the end of atable of values for the shift schedule graphs (FIGS. 14B-D), i.e. X_(o); Y_(o) ; X_(R) ; Y_(R) ; X_(n) ; Y_(n). If the method is not at the endof the table, the methodology advances to block 1020 and goes to thenext row of the table. The methodology then loops back to diamond 1010.

If the methodology is at the end of the table at diamond 1018, themethodology advances to block 1022 and concludes or determines that thevalue for X is not in the table but greater than X_(n) (FIG. 15B), andgets the Y_(n) value, i.e. the last value Y_(n) from the data tablebased on the value for X_(n). The methodology then returns or exitsthrough bubble 1016.

SHIFT LOGIC METHOD

The shift logic block 828 contains twelve unique shift programs. Theshift logic block 828 identifies the shift logic or routine to beexecuted. For example, if the transmission 100 is in first gear and theshift schedule output (SSOUTP) changes to call for second gear, theshift selection block 804 picks a SHCODE and shift logic block 828identifies and executes the SHCODE for first to second (1-2) logic.

Each of the twelve different shifts involves extensive calculations andlogical manipulations to determine the "ON" or "OFF" states of thesolenoids of the solenoid-actuated valves 630, 632, 634 and 636 (FIGS.5A-L) for engaging (applying) or disengaging (releasing) of the clutchesfor the shifts. These shifts are organized into three sets of shifts asfollows: upshifts 1-2, 2-3, 3-4 and 2-4; downshifts 2-1, 3-1, 4-3, 4-2and 3-2; and garage shifts N-l, N-R and R-N.

The methodology consists of three major routines, one for each of theabove sets of shifts. To make this possible, a "Control Table" method isused. The key parametric entities are imbedded in a shift control tableas follows:

    ______________________________________                                        SHIFT CONTROL TABLE                                                           FORMAT               NUMBER OF BYTES                                          ______________________________________                                        RELEASE ELEMENT BIT  (1)                                                      APPLY ELEMENT BIT    (1)                                                      ADDR. OF VF (APPLY)  (1)                                                      ADDR. OF VF (REL.)   (1)                                                      NI GEAR (initiating ratio)                                                                         (2)                                                      NJ GEAR (destination ratio)                                                                        (2)                                                      DESTINATION ELEMENT MASK                                                                           (1)                                                      ______________________________________                                    

All calibration variables are segregated into a separate table called a"Volume Table" for example, as follows:

    ______________________________________                                        VOLUME TABLES                                                                 CLUTCH IDENTIFIER   ELEMENT                                                   ______________________________________                                        103                 QF CU.INCH/MS.                                            54                  QV CU.INCH/MS.                                            1802                C CU. INCHES                                              18514               VA CU. INCHES                                             17                  SLOPE QF                                                  74                  SLOPE QV                                                  VFLRC               ADDR. OF "VF"                                             ______________________________________                                    

Thus, during product development, the key flow-rate and volumetricparameters can be efficiently and manageably altered. As a result, eachmajor shift routine (upshift, downshift or garage shift) can do one ofits many shifts just by getting the necessary fixed parameters from theshift control table and the calibration (volumetric, flow rates, etc.)data from the volume tables.

Accordingly, this shift logic method provides the following advantages:efficient management of ROM and RAM resources of the transmissioncontroller 3010; efficiency during product calibration cycle; and defectpreventiveness during development due to the segregation by upshifts,downshifts and garage shifts and by fixed versus calibration parameters.

Referring to FIG. 16A, for upshifts of the shift logic block 828 of FIG.12, the methodology enters the start or top of shift in the shift logicblock 828 through bubble 1100. The methodology advances to diamond 1102and determines whether the torque converter 110 is presently in thelock-up mode as previously described. If the torque converter 110 ispresently locked, the methodology advances to block 1104 and instructsthe transmission controller 3010 to unlock the torque converter 110 whenslip from the present gear toward the target gear begins, i.e. fromfirst to second gear. The methodology then advances to block 1106.

At diamond 1102, if the torque converter 110 is not in the lock-up mode,the methodology advances to block 1106. At block 1106, the transmissioncontroller 3010 computes variables, such as t_(f) (time remaining tonearly fill the apply clutch, t_(r) (time to nearly release), DC_(t)(torque phase duty cycle) etc., states/flags to be used in shift logicequations and intercepts/calculates variables used for "learning", to bedescribed under section heading "LEARN METHODOLOGY" at the end of theshift. The methodology advances to block 1108 and solves a predeterminedlogic equation for the apply element such as a clutch. The methodologythen advances to diamond 1110 and determines whether the solenoid forthe apply element or oncoming clutch should be logically "ON" based oncalculated speeds, throttle angle and SSOUTP.

It should be appreciated that the friction element (apply or release)such as a clutch is turned logically "ON or OFF" by either theenergization or de-energization of the solenoid-actuated valve. Itshould also be appreciated that "ON" or "OFF" can be can be either"applying or venting" of the function element.

If the apply clutch should be ON, the methodology advances to diamond1112 and determines whether the apply clutch is under duty cyclecontrol, i.e. solenoid-actuated valve to the clutch is cycled "ON" and"OFF", by looking for a flag previously set. If the apply clutch is notunder duty cycle control, the methodology advances to block 1114 andturns ON or applies the apply clutch by energizing or de-energizing thesolenoid of the respective solenoid-actuated valve. If the apply clutchis under duty cycle control, the methodology advances to block 1116 andstarts or continues the duty cycle.

At diamond 1110, if the apply clutch should not be ON, or applied themethodology advances to block 1118 and turns OFF or disengages the applyclutch. The methodology advances from blocks 1114, 1116 or 1118 to block1120 and solves a predetermined the release clutch or off-going clutchlogic equation. The methodology advances to diamond 1122 and determineswhether the release clutch or off-going clutch should be ON based oncalculated speeds, throttle angle and SSOUTP. If the release clutchshould not be ON, the methodology advances to block 1124 and turns OFFor disengages the release clutch. The methodology then returns or exitsthrough bubble 1126.

At diamond 1122, if the release clutch should be ON or applied, themethodology advances to diamond 1128 and determines whether the releaseclutch is under duty cycle control by looking for a flag as previouslydescribed. If the release clutch is not under duty cycle control, themethodology advances to block 1130 and turns ON or applies the releaseclutch. The methodology returns or exits through bubble 1126.

At diamond 1128, if the release clutch is under duty cycle control, themethodology advances to block 1132 and starts or continues the dutycycle. The methodology exits through bubble 1126.

Referring to FIGS. 16B and 16C, the downshift logic for the shift logicblock 828 of FIG. 12 is shown. The methodology enters through bubble1200. The methodology advances to diamond 1204 and determines whetherthe torque converter 110 is unlocked as previously described. If thetorque converter 110 is not unlocked, the methodology advances to block1206 and aborts partial or full lock-up operation. The methodologyadvances to block 1208.

At diamond 1204, if the torque converter 110 is unlocked, themethodology advances to block 1208. At block 1208, the transmissioncontroller 3010 computes variables and states of flags to be used insimilar shift logic equations of the upshift logic. The methodologyadvances to diamond 1210 and determines whether the present shift is adownshift to first gear by the SSOUTP. If the present shift is adownshift to first gear, the methodology advances to diamond 1212 anddetermines whether the solenoid switch valve 610 has moved to the lowgear position (see FIG. 5E). The position of the solenoid switch valve610 is determined by checking pressure switch data from the pressureswitches 646, 648 and 650 within a predetermined time period. If thesolenoid switch valve 610 has moved to the low gear position, themethodology advances to diamond 1214 and determines whether the solenoidswitch valve 610 has moved back to the high gear or lock-up position(See FIG. 5F). If the solenoid switch valve 610 has moved back to thehigh gear position, the methodology returns or exits through bubble1216.

At diamond 1212, if the solenoid switch valve 610 has not moved to thelow gear position, the methodology advances to block 1218 and executessolenoid switch valve control logic (energizing and de-energizing thesolenoid-actuated valves 634 and 636), previously described, to move thesolenoid switch valve 610 to the low gear position. The methodology thenadvances to block 1220.

At diamond 1214, if the solenoid switch valve 610 has not moved back tothe high gear position, the methodology advances to block 1220. Atdiamond 1210, if the present shift is not a downshift to first gear, themethodology advances to block 1220. At block 1220, the transmissioncontroller 3010 solves the release clutch shift logic equation. Themethodology advances to diamond 1222 and determines whether the releaseclutch should be turned ON or applied as previously described. If therelease clutch should not be turned ON, the methodology advances toblock 1224 and turns OFF or disengages the release clutch.

At diamond 1222, if the release clutch should be turned ON, themethodology advances to diamond 1226 and determines whether the releaseclutch is in the duty cycle mode as previously described. If the releaseclutch is not in the duty cycle mode, the methodology advances to block1228 and turns ON or applies the release clutch. If the release clutchis in the duty cycle mode, the methodology advances to block 1230 andstarts or continues the release clutch duty cycle. The methodologyadvances from blocks 1224, 1228 and 1230 to diamond 1232.

At diamond 1232, the transmission controller 3010 determines whether thepresent shift is a downshift to first gear as previously described. Ifthe present shift is a downshift to first gear, the methodology advancesto diamond 1234 and determines whether the solenoid switch valve 610 hasmoved to the low gear position as previously described. If the solenoidswitch valve 610 has not moved to the low gear position, the methodologyexits or returns through bubble 1236. If the solenoid switch valve 610has moved to the low gear position, the methodology advances to block1238. If the present shift is not a downshift to first gear at block1232, the methodology advances to block 1238.

At block 1238, the transmission controller 3010 solves the shift logicequation for the apply clutch and intercepts/calculates the necessarydata for "learning" at the end of the shift to be describedsubsequently. The methodology advances to diamond 1240 and determineswhether to turn ON the apply clutch.

If the transmission controller 3010 determines not to turn ON the applyclutch, the methodology advances to block 1242 and turns OFF ordisengages the apply clutch. If the transmission controller 3010determines to turn ON the apply clutch, the methodology advances todiamond 1244 and determines whether the apply clutch is in the dutycycle mode as previously described. If the apply clutch is not in theduty cycle mode, the methodology advances to block 1246 and turns ON theapply clutch. If the apply clutch is in the duty cycle mode, themethodology advances to block 1248 and starts or continues the applyclutch duty cycle. The methodology advances from blocks 1242, 1246 and1248 to block 1250.

At block 1250, the transmission controller 3010 solves a non-controllingclutch shift logic equation similar to the controlling shift logicequations needed for the shift to occur as previously described. Aclutch other than one needed to make the shift or gear change is calledthe non-controlling clutch. This clutch is cycled ON and OFF by theappropriate solenoid-actuated valve to improve shift quality. Themethodology advances from block 1250 to diamond 1252 and determineswhether to turn ON or apply the non-controlling clutch based oncalculated speeds, throttle angle and SSOUTP. If the transmissioncontroller 3010 determines not to turn ON the non-controlling clutch,the methodology advances to block 1254 and turns OFF or disengages thenon-controlling clutch. If the transmission controller 3010 determinesto turn ON the non-controlling clutch, the methodology advances to block1256 and turns ON the non-controlling clutch. The methodology returns orexits from blocks 1256 and 1256 through bubble 1258.

Referring to FIG. 16C, the garage shift methodology for the shift logicblock 828 of FIG. 12 is shown. The methodology enters the shift logicblock 828 through bubble 1300. The methodology advances to block 1302and turns the non-controlling clutches either ON or OFF, i.e. engages ordisengages the clutches not needed to perform the garage shifts. Themethodology advances to diamond 1304 and determines whether the presentshift is a garage shift to first gear by looking at SHCODE. If thepresent shift is a garage shift to first gear, the methodology advancesto diamond 1306 and determines whether the solenoid switch valve 610 hasmoved to the first gear position (FIG. 5E) as previously described. Ifthe solenoid switch valve 610 has not moved to the first gear position,the methodology advances to block 1308 and performs solenoid switchvalve control logic as previously described. The methodology then exitsor returns through bubble 1310.

At diamond 1304, if the shift is not a garage shift to first gear, themethodology advances to block 1312. At diamond 1306, if the solenoidswitch valve 610 has moved to the first gear position, the methodologyadvances to block 1312. At block 1312, the transmission controller 3010computes variables and states of flags to be used in a controlling shiftlogic equation similar to those in the upshift logic. The methodologyadvances to block 1314 and solves the controlling clutch shift logicequation. The methodology advances to diamond 1316 and determineswhether to turn ON the controlling clutch as previously described. Ifthe controlling clutch is not to be turned ON, the methodology advancesto block 1318 and turns OFF the controlling clutch. If the controllingclutch is to be turned ON, the methodology advances to diamond 1320 anddetermines whether the controlling clutch is under duty cycle control aspreviously described. If the controlling clutch is not under duty cyclecontrol, the methodology advances to block 1322 and turns ON thecontrolling clutch. If the controlling clutch is under duty cyclecontrol, the methodology advances to block 1324 and starts or continuesthe apply clutch duty cycle. The methodology returns or exits fromblocks 1318, 1322 and 1324 through bubble 1326.

TORQUE CONVERTER LOCK-UP METHOD

Partial lock-up (PLU) of the torque converter 110 is used in transitionfrom unlock (UL) to full lock-up (FL). This occurs when the transmission100 is operating in "top gear", i.e. the highest gear availableaccording to the shift lever position 606 (PRNODDL). PLU is used forsteady-state slight slippage operation. From either PLU or FL operation,a return to UL operation is effected upon any of the followingconditions: throttle angle less than a predetermined angle, e.g., 2degrees, turbine speed N_(t) less than a predetermined speed, e.g., 1400r.p.m. in fourth gear; start of a downshift; start of a speed change inan upshift or; application of the brakes of the vehicle.

In PLU, the methodology controls the initial application of the lock-upclutch assembly 186 and maintains a limited slip condition if FL is notused. The duty cycle (DC, % ON period) of the low/reverse clutchsolenoid-actuated valve 636 is calculated according to the following:

    DC=DC (i-1)+deltaDC, where

    deltaDC=-0.8 delta DC (i-1)+K(E.sub.a -A).

The methodology attempts to control slip at a predetermined value, e.g.80 r.p.m. In each 0.028 second cycle, the methodology finds the sliperror, which is N_(e) minus N_(t) minus a predetermined value such as 80r.p.m. This and three previous slip errors are used to calculate ananticipated slip error E_(a). The difference between E_(a) and ananticipated error modification term A is multiplied by a gain K to givea duty cycle increment term, i.e. either the "ON" or "OFF" time of thelow/reverse clutch solenoid-actuated valve 636 to cycle the LU switchvalve 614. In effect, this provides a proportional/integral/differentialcontrol with some filtering included because of the poor quality of theN_(e) data. The other duty cycle increment term consists of a constant,such as -0.8, times the previous duty cycle increment. This provides alead/lag to improve system stability.

This basic operation is modified in a number of ways depending onconditions. The gain K is reduced by half in second gear in recognitionof the higher plant gain due to higher line pressure. Also, the gain Kis high at large errors in order to gain control more quickly, and lowat small errors in order to improve stability. The "A" term provides thefollowing features: for values of error above 30 r.p.m., it causes thelogic to try to control the rate of error or slip reduction to about 300r.p.m./sec., rather than controlling the error to zero as above, inorder to provide a smooth pull-in; and for values of slip below 10r.p.m., it backs the duty cycle out somewhat faster than it wouldotherwise, in order to reduce the exposure to FL torsionals at lowN_(t).

The initial duty cycle is 60% in third or fourth, and 55% in secondbecause of the higher line pressure. This value is also the upper limitfor the first five cycles. Otherwise, during tip-ins (operator backs offthe accelerator pedal of the vehicle), the duty cycle would incrementrapidly before the lock-up clutch 186 applies, causing a sharp pull-in.

For full lock-up, once PLU has brought the slip down to 80 r.p.m., theduty cycle simply increments by 1% per cycle in order to finish thepull-in smoothly. Once 90% is reached, the methodology goes to full ON.In order to prevent immediate FL during tip-ins before the lock-upclutch 186 is applied, 0.25 seconds of PLU is required.

Referring to FIG. 17, the torque converter lock-up methodology for thepartial lock-up block 834 of FIG. 12 is shown. At the start of thelock-up analysis in bubble 1600, the methodology advances to block 1602and checks all conditions that may preclude partial lock-up operation aspreviously described (i.e. to unlock). The methodology advances todiamond 1604 and determines whether any of the conditions in block 1602prevent partial lock-up operation. If any condition prevents partiallock-up operation, the methodology advances to block 1606 and sets allconditions (resets all bits in the transmission controller 3010 thatwere used during partial lock-up) to unlock the torque converter 110 ofthe transmission 100. The methodology then returns through bubble 1608.

At diamond 1604, if there are no conditions which prevent partiallock-up operation, the methodology advances to diamond 1610 anddetermines whether the transmission controller 3010 is presently partiallocking the torque converter 110 by looking for the absence of a flag aspreviously described. If partial lock-up is presently happening, themethodology advances to block 1612 and checks the position of thethrottle and turbine speed N_(t) for conditions that require unlockoperation as previously described. The methodology advances to diamond1614 and determines whether unlock (UL) operation is required based onthe check in block 1612. If unlock operation is required, themethodology advances to block 1606 previously described to set allconditions to unlock the torque converter 110.

If partial lock-up is not presently happening at diamond 1610 or unlockoperation is not required at diamond 1614, the methodology advances toblock 1616 and checks for conditions previously described that wouldallow partial lock-up operation (i.e. prevent unlock from occurring).The methodology advances to diamond 1618 and determines whether all theconditions in block 1616 were satisfied. If all the conditions were notsatisfied, the methodology returns.

At diamond 1618, if all the conditions in block 1616 were satisfied, themethodology advances to block 1620 and sets the initial conditions (i.e.bits in the transmission controller 3010) for going from unlock topartial lock-up. The methodology advances to diamond 1622 and determineswhether the methodology is at the start of a partial lock-up timeperiod, i.e. the starting point of a time period for the duty cycle ofvalve 636. This is accomplished by looking at a counter in thetransmission controller 3010 which cycles from zero to four (zero beingthe start of a time period). If the methodology is not at the start of apartial lock-up time period, the methodology returns.

If the methodology is at the start of a partial lock-up time period, themethodology advances to block 1624 and checks for conditions that allowfull lock-up (FL) operation (i.e. prevent unlock from occurring). Themethodology advances to diamond 1626 and determines whether full lock-upof the torque converter 110 is already occurring by looking for a flagas previously described. If full lock-up is not occurring, themethodology advances to diamond 1628 and determines whether allconditions checked in block 1624 allow full lock-up operation. If allconditions allow full lock-up operation or full lock-up is alreadyoccurring at diamond 1626, the methodology advances to block 1630 andsolves the equations, previously described, for full lock-up. Themethodology then returns.

At diamond 1628, if any of the conditions in block 1624 do not allowfull lock-up operation, the methodology advances to block 1634 andsolves the equations, previously described, for partial lock-up. Themethodology then advances to diamond 1636 and determines whether allchecks that preclude partial lock-up operation, as previously described,were satisfied. If all checks or conditions were not satisfied, themethodology advances to diamond 1638 and determines whether the faultcount is at or exceeds a predetermined maximum value. If the fault countis at the predetermined maximum value, the methodology advances to block1640 and performs unlock operation and stores the fault codes in memoryof the transmission controller 3010. If the fault count is not at thepredetermined maximum value, the methodology advances to block 1642 andupdates the fault count. The methodology returns from blocks 1640 and1642. Also, if all safety checks were satisfied at diamond 1626, themethodology returns.

ADAPTIVE IDLE METHOD

The present invention provides an "adaptive idle" method. Adaptive idleis a feature whereby in the idle condition with the engine idling andthe vehicle stopped in "OD", "D", or "L", the PRNODDL position is almostlike a neutral, i.e. resulting in a turbine-free idle, in contrast to anormal turbine-stalled idle. This reduction in torque converter torquereduces engine torque, and thus improves idle fuel consumption.

A true neutral idle under these conditions is not possible, because thisimplies a complete release of one of the first gear friction elements(the underdrive clutch 302 in this case). Then, when the throttle isopened, the clutch apply cavity must fill, with the engine and turbinerunning away before the clutch can apply; a highly unsatisfactory launchwill result.

In the near-neutral adaptive idle strategy, the underdrive clutch 302 ismaintained at a very lightly applied condition, ready to pick up torquewhen the throttle is opened. This condition is inferred from a slightdifference between engine N_(e) and turbine N_(t) speeds, and thus thestrategy is to control the duty cycle of the underdrive clutchsolenoid-actuated valve 630 for the underdrive clutch 302 to maintainthis difference. The target turbine speed (N_(j)) is 50 r.p.m. belowengine speed N_(e) if the engine speed N_(e) is at or below its target(AIS), then decreases as the engine speed N_(e) increases above this.The duty cycle control is a proportional/integral/differential controlbased on turbine speed error (actual versus target).

If the throttle is opened or if the vehicle is rolling at more than afew miles per hour, adaptive idle exit is triggered. It may be thatbrake-off triggers the exit as well; this is intended as a feature toprevent a driver from leaving the car while it is in adaptive idle, byreturning it to a normal creep idle condition if the driver removestheir foot from the brake. The adaptive idle exit routine increases theduty cycle until turbine deceleration is detected, then goes to aproportional/integral turbine deceleration control, with desired turbinedeceleration increasing with throttle opening. A direct throttle effecton duty cycle is also included in order to get earlier response and thusprevent runaway as previously described.

To allow for quick response on vehicle launch, the underdrive clutch 302is not fully released, but is allowed to slip. The amount of slip iscontrolled by duty cycling the underdrive clutch 302 using a "steadystate" adaptive idle equation. Upon vehicle launch (adaptive idle exit),the rate at which the underdrive clutch 302 is applied is controlled byduty cycling the underdrive clutch 302 using an "exit" adaptive idleequation to allow for smooth clutch application. Since adaptive idleunloads the engine when the vehicle is brought to a stop, the engine canbe idled at a lower speed which will cause an increase in fuel economy.

Referring to FIG. 18A, the adaptive idle methodology 1700 is shown. Atthe start of the adaptive idle in bubble 1702, the methodology advancesto block 1704 to solve an adaptive idle conditions equation. Theadaptive idle condition equations may be defined as follows:

SET: (Throttle angle less than 2°) and (N_(o) less than 250 r.p.m.) and(BRAKE-ON)

CLEAR: (Throttle angle greater than 4°) or (N_(o) greater than or equalto 250 r.p.m.) or (BRAKE-OFF)

The above conditions have to be met to get into or out of adaptive idle.The result of the above equations is for setting or clearing a flagwhich is stored. The methodology advances to diamond 1706 and determineswhether adaptive idle is in a "steady state" mode (FIG. 18C) by lookingfor a flag or performing calculations of speed for example. If adaptiveidle is not in the steady state mode, the methodology advances todiamond 1708.

At diamond 1708, the transmission controller 3010 determines whetheradaptive idle is in an adaptive idle "exit" mode (FIG. 18C) by lookingfor a flag or performing calculations of speed for example. If not, themethodology advances to diamond 1710 and determines whether the adaptiveidle conditions previously described are true by looking for a flag ofblock 1704. If the adaptive idle conditions are not true, themethodology advances to block 1712 and turns ON or applies theunderdrive clutch 302. The methodology then returns through bubble 1714.

At diamond 1710, if the adaptive idle conditions are true, themethodology advances to block 1716 to solve the adaptive idle entranceequation, representing part of the curve illustrated in FIG. 18C. Theadaptive idle entrance equation may be defined as follows:

T(i)=0 until [N_(t) (i) is greater than first gear N_(t) plus 50 r.p.m.]and [N_(t) (i) is greater than 100 r.p.m.], then

T(i)=7700 for one cycle

In the above equations, T(i) is the calculated ON time of the underdriveclutch solenoid-actuated valve 630 at the start of each cycle, and N_(t)(i) is the current turbine speed. The underdrive clutch 302 is keptfully OFF (i.e. T(i)=0) until adaptive idle conditions are met. Themethodology advances to diamond 1718 and determines whether the entranceinto adaptive idle is complete by looking for a flag or performingcalculations of speed for example. If the entrance is not complete, themethodology advances to block 1720 and turns OFF or disengages theunderdrive clutch 302. If the entrance is complete, the methodologyadvances to block 1722 and initializes predetermined variables such asthe percent ON time (i.e. T(i)=7700 for one cycle) for adaptive idlesteady state mode. The methodology advances to block 1724 and starts theduty cycle of the solenoid-actuated valve 630 for the underdrive clutch302. The methodology then returns through bubble 1714.

At diamond 1706, if the transmission 100 is in the adaptive idle steadystate mode, the methodology advances to diamond 1726 and determineswhether the adaptive idle conditions previously described in block 1704are true by looking for a flag. If the adaptive idle conditions aretrue, the methodology advances to block 1728 and solves the adaptiveidle steady state equation each predetermined time period of the dutycycle (See FIG. 18B). The steady state equation may be defined asfollows:

    T(i)=T(i-1)+36[N.sub.t (i)-N.sub.t (i-1)]-24[N.sub.t (i-1)-N.sub.t (i-2)]+4[N.sub.t (i)-N.sub.d ]

where:

T(-1)=previous cycle ON time for the solenoid of the solenoid-actuatedvalve; and

N_(d) =desired turbine speed.

If the adaptive idle conditions are not true, the methodology advancesto block 1730 and initializes predetermined variables previouslydescribed for the adaptive idle exit mode, representing part of thecurve illustrated in FIG. 18C. The exit equation may be initialized asfollows:

T(i)=T_(AI) +8400 until (α_(t) is less than-500), then

T(i)=0.8T_(AI) +2240 for one cycle, where:

T_(AI) =last T(i) in adaptive idle before adaptive idle exit

The methodology advances from block 1728 and 1730 to block 1732 andcontinues the duty cycle for the underdrive clutch 302. The methodologythen returns through bubble 1714.

At diamond 1708, if the transmission 100 is in the adaptive idle exitmode, the methodology advances to diamond 1734 and determines whetherthe adaptive idle conditions in block 1704 previously described are trueby looking for a flag. If the adaptive idle conditions are true, themethodology advances to block 1716 previously described to solve theadaptive idle entrance equation. If the adaptive idle conditions are nottrue, the methodology advances to diamond 1736 and determines whether apredetermined adaptive idle exit time has been exceeded by looking at atimer. If the adaptive idle exit time has been exceeded, the methodologyadvances to block 1738 and ends adaptive idle operation. The methodologyadvances to block 1740 and turns ON or applies the underdrive clutch302. The methodology then returns through bubble 1714.

At diamond 1736, if the adaptive idle exit time has not been exceeded,the methodology advances to diamond 1742 and determines whether thetransmission 100 is presently in first gear by looking at speed ratiosof N_(t) to N_(o). If the transmission 100 is presently in first gear,the methodology advances to block 1738 previously described to endadaptive idle operation. If the transmission 100 is not presently infirst gear, the methodology advances to block 1744 and solves theadaptive idle exit equation each time period of the duty cycle. The exitequation may be defined as follows:

    T(i)=T(i-1)+52[N.sub.t (i)-N.sub.t (i-1)]-34[N.sub.t (i-1)-N.sub.t (i-2)]+700+14Thr(i)+258[Thr(i)-Thr(i-1)],

where: Thr(i)=current throttle angle.

The methodology advances to block 1746 and continues the duty cycle ofthe solenoid-actuated valve 630 for the underdrive clutch 302. Themethodology then returns.

PRNODDL METHOD

The PRNODDL method is used to read sensors sensing the position of themanual lever 578 to determine the driver-selected operating mode orshift lever position 606, i.e. PRNODDL. Referring to FIG. 4B, the manualshaft 591 is connected to the manual lever 578. Neutral start groundingcontacts or contact switch sensors (NS₁ and NS₂) threadably engage thetransmission case 102 and are in radial alignment with a pair ofcircumferentially spaced outwardly extending projections or metal areas3084 (FIG. 19) when the shift lever position is park P. The metal areas3084 extend through an insulator or cap member 578a made of plastic anddisposed partially and circumferentially about the manual lever 578. Thecontact switch sensors NS₁ and NS₂ can only be grounded when they are inradial alignment with the metal areas 3084 on the manual lever 578. Afurther detailed description of the structure is found under the"ADAPTIVE CONTROL CIRCUITS" heading.

The gear selector or shift lever position (PRNODDL) is measured by thecontact switch sensors NS₁ and NS₂. Reverse light contacts (RL₁ and RL₂in FIG. 19) are connected to the backup lights of the vehicle in a knownmanner. NS₁ can only be grounded in park P and neutral N. The contactswitch sensors NS₁ and NS₂ cannot be grounded with RL contacts closed.As a result, the contact switch sensors NS₁ and NS₂ make electricalcontact with the RL contacts when the manual lever 578 is in the reverseposition. Hence, continuity to the backup lights can only exist inreverse R.

Referring to FIG. 19, the PRNODDL method is shown schematically. Themanual lever 578 and cap member 578a act as a cam and the contact switchsensors NS₁ and NS₂ act as the follower. NS₁ and NS₂ provide a binaryzero input when the center terminal or spring loaded contact pin 3082 isgrounded by contacting the metal areas 3084 on the manual lever in 578.RL₁ and RL₂ provide a zero whenever the manual lever 578 pushes springloaded contact pin 3082 on the contact switch sensors NS₁ and NS₂ upwarddisconnecting two internal contacts 3088 of the contact switch sensorsNS₁ and NS₂ with the RL contacts. For example, in P, NS₁, NS₂, and RL₁,RL₂ provide a zero input. The remaining inputs are shown in the tablebelow:

    ______________________________________                                        P           R           N        OD       D       L                           ______________________________________                                        NS.sub.1                                                                            0     0 1 1   1   1   0   0 1  1    1   1   1   1                       RL.sub.1                                                                            0     0 0 0   1   0   0   0 0  1    0   0   0   0                       NS.sub.2                                                                            0     1 1 1   1   1   1   1 1  1    1   1   1   0                       RL.sub.2                                                                            0     0 0 1   1   1   1   0 0  0    0   1   0   0                       CODE  P     T.sub.1 T.sub.2 D                                                                     R   D   N   T.sub.1 T.sub.2                                                                    OD   T.sub.2                                                                           D   T.sub.2                                                                           L                       ______________________________________                                    

The PRNODDL codes are verified by pressure switch data to be describedherein. If the engine of the vehicle is running (N_(e) is less than 500r.p.m.), the transmission controller 3010 checks its permanent memory tosee if the PRNODDL code determined above corresponds with pressureswitch data from the pressure switches 646, 648 and 650 (FIGS. 5A-L) atthe last "Engine running" check ("PRNODDL OK"). If the data corresponds,the transmission controller 3010 displays a valid PRNODDL code. If datadoes not correspond, the transmission controller 3010 displays "??" andreports "PRNODDL Failures--Engine Off" to permanent memory.

If the engine is running at or above a predetermined speed (N_(e) equalor greater than 500 r.p.m.), the transmission controller 3010 reads thePRNODDL code as above-described. If PRNODDL code is valid, thetransmission controller 3010 verifies with the pressure switch data inthe table below:

    ______________________________________                                        PRNODOL CODE/                                                                 PRESSURE SWITCH   LR       2-4      OD                                        ______________________________________                                        PN                ON       OFF      OFF                                       R                 OFF      OFF      OFF                                       OD,D,L            ON       ON       ON                                        ______________________________________                                    

SHIFT LEVER POSITION METHODOLOGY

The transmission control logic relies on the Shift Lever Position (SLP)methodology to identify the mode of transmission operation selected bythe driver to provide hysteresis between the PRNODDL positions, and topermit limited operation of the transmission controller 3010 withoutfunctioning PRNODDL contact switch sensors (NS₁, NS₂, RL₁, RL₂) byutilizing pressure switch data from the pressure switches 646, 648 and650 (FIGS. 5A-L) to identify the three hydraulic modes of operation(i.e. reverse R, neutral N and drive D). In the SLP methodology, P, R,N, and OD (overdrive) PRNODDL codes are accepted as being valid withoutregard to pressure switch data since the corresponding hydraulic porting(park and neutral are identical) condition must occur first. Testing forSLP position (checking pressure switch input) is only done withtemporary or invalid codes present since this is the area wherehydraulic porting changes occur.

Referring to FIGS. 20A and 20B, the shift lever position (SLP)methodology is shown. At the beginning in block 1800, the methodologyadvances to diamond 1802 and determines whether the PRNODDL code (PC)from the sensors (NS₁, NS₂, RL₁, RL₂) is equal to a code for park P,neutral N or a temporary code (T₁) stored in memory in the transmissioncontroller 3010. If PC is equal to park, reverse or a temporary code,the methodology advances to block 1804 and sets the shift lever position(SLP) 606 (FIGS. 5A-L) equal to neutral. If PC is not equal to park,neutral or a temporary code, the methodology advances to diamond 1806and determines whether PC is equal to reverse R or overdrive OD. If PCequals reverse or overdrive, the methodology advances to block 1808 andsets the SLP 606 equal to PC. If PC is not equal to reverse oroverdrive, the methodology advances to diamond 1810 and determineswhether PC is in drive D or low L. If PC is drive or low, themethodology advances to diamond 1812 and determines whether SLP 606 isreverse or neutral. If SLP 606 is not reverse or neutral, themethodology advances to diamond 1813 and determines whether a neutral tofirst gear (N-1) shift is in progress by looking for a flag. If aneutral to first gear shift is not in progress, the methodology advancesto block 1808 previously described and sets SLP 606 equal to PC.

If SLP 606 is reverse or neutral at diamond 1812, or PC does not equaldrive or low at diamond 1810, or a neutral to first gear shift is inprogress, the methodology advances to diamond 1814 and determineswhether PC equals an invalid code (I) stored in memory. If PC is aninvalid code, the methodology advances to diamond 1816 and determineswhether a PRNODDL FAIL (PF) flag has been set. If PF has not been set,the methodology advances to block 1817 and determines whether a count non a counter is greater than a predetermined value such as 15. If thecount n is greater than the predetermined value, the methodologyadvances to block 1818 and sets PF. If the count n is not greater thanthe predetermined value, the methodology advances to block 1819 andincrements the count n. The methodology then advances to diamond 1821.If PC is not an invalid code at diamond 1814, the methodology advancesto block 1820 and sets the count n on the counter equal to apredetermined value such as zero. The methodology then advances todiamond 1821. If PF was previously set at diamond 1816 or once the PFflag has been set at diamond 1818, the methodology advances to diamond1821 and determines whether SLP 606 is reverse. If SLP is reverse, themethodology advances to block 1822 and turns ON the low/reverse clutchsolenoid-actuated valve 636. The methodology then advances to diamond1823 and determines whether the low/reverse pressure switch 650 is equalto one or pressurized. If the low/reverse pressure switch 650 is equalto one, the methodology advances to block 1824 and sets SLP 606 equal toneutral. This occurs because the low/reverse pressure switch 650 ispressurized or producing a signal equal of one (See FIG. 5A) only whenthe transmission 100 is not in reverse gear and the low/reverse clutch310 is being applied. If the low/reverse pressure switch 650 is notequal to one, the methodology advances to block 1837 to be described.

If SLP 606 is not reverse at diamond 1821, the methodology advances todiamond 1826 and determines whether SLP 606 is equal to neutral. If SLPis neutral, the methodology advances to block 1827 to set an SLP testflag. The methodology then advances to diamond 1828 and determineswhether the overdrive pressure switch 646 is equal to one orpressurized. If the overdrive pressure switch 646 equals one, themethodology advances to block 1824 and sets a count Z on a counter equalto a predetermined value such as 43. The methodology then advances toblock 1830 and sets SLP 606 equal to overdrive OD. This occurs becausethe overdrive clutch 304 is being applied when the overdrive pressureswitch 646 is pressurized or producing a signal equal to one (See FIG.5H). If the overdrive pressure switch 646 does not equal one, themethodology advances to diamond 1832 and determines whether thelow/reverse solenoid-actuated valve 656 is ON, the pressure switches646, 648 and 650 are not pressurized or are equal to zero (See FIG. 5C)and N_(e) is greater than a predetermined value, i.e. 500 r.p.m. If thatcriteria is true, the methodology advances to block 1834 and sets SLP606 equal to reverse. If that criteria is not true, the methodologyreturns.

At diamond 1826, if SLP 606 is not neutral, the methodology advances todiamond 1836 and determines whether engine speed N_(e) is less than apredetermined speed, i.e. 500 r.p.m. If engine speed N_(e) is less thanthe predetermined speed, the methodology advances to block 1837 anddecrements the count Z on the counter by a predetermined value. Themethodology then advances to block 1838 and clears the SLP test flag.The methodology then returns. If engine speed N_(e) is not less than thepredetermined speed, the methodology advances to diamond 1839 anddetermines whether a shift is in progress or occurring by looking for aflag. If the shift is in progress, the methodology advances to diamond1840 and determines whether a neutral to first gear shift is in progressas previously described. If a neutral to first gear shift is not inprogress, the methodology advances to block 1837 previously described.If the shift is not in progress, or a neutral to first gear shift is inprogress, the methodology advances to diamond 1841 and determineswhether the LU switch valve 614 is being applied as a result of thelow/reverse element solenoid-actuated valve 636 being energized or onand low/reverse pressure switch 650 equals one and both the two/four 648and overdrive 646 pressure switches equal zero. If that criteria istrue, the methodology advances to block 1842 and sets SLP 606 equal toneutral. If that criteria is not true, the methodology advances todiamond 1843 and determines whether the transmission 100 is presently infourth gear by calculating speeds. If the transmission 100 is presentlyis fourth gear, the methodology advances to diamond 1844 and determineswhether the pressure switches 646, 648 and 650 equal zero. If thepressure switches equal zero, the methodology advances to block 1842previously described. If all the pressure switches 646, 648 and 650 donot equal zero, the methodology advances to block 1837 previouslydescribed.

If the transmission 100 is not presently in fourth gear, the methodologyadvances to diamond 1845 and determines whether count Z equals apredetermined value such as zero. If Z does not equal zero, themethodology advances to block 1837 previously described. If Z equalszero, the methodology advances to diamond 1846 and determines whetherthe transmission 100 is presently in first gear by speed calculations,the low/reverse pressure switch 650 equals one and turbine speed N_(t)is greater than a predetermined r.p.m., or the pressure switches 646,648 and 650 equal zero, or the low/reverse pressure switch 650 equalsone and a neutral to first gear shift is in progress. If any of thatcriteria is not true, the methodology advances to diamond 1847 anddetermines whether the SLP test flag has been set. If the SLPT flag hasnot been set, the methodology advances to block 1837 previouslydescribed. If the SLP test flag has been set, the methodology advancesto block 1848 and sets Z equal to a predetermined value such as 43. Themethodology then advances to block 1838 previously described. If any ofthe criteria in diamond 1846 is true, the methodology advances to block1849 and sets the SLP test flag and starts or continues a SLP timer(SLPT). The methodology then advances to diamond 1850 and determineswhether the time on the SLPT timer is greater than a predetermined timeperiod. If the time on the SLPT timer is not greater than thepredetermined time period, the methodology returns. If the time on theSLPT timer is greater than the predetermined time period, themethodology advances to diamond 1851 and determines whether thetransmission 100 is operating in first gear by performing speedcalculations. If the transmission 100 is not operating in first gear,the methodology advances to block 1852 and sets SLP 606 equal toneutral. The methodology then advances to block 1838 previouslydescribed. If the transmission 100 is operating in first gear, themethodology advances to diamond 1854 and determines whether thelow/reverse pressure switch 650 equals one. If the low/reverse pressureswitch 650 does not equal one, the methodology advances to block 1856and sets SLP 606 equal to reverse (See FIG. 5C). The methodology thenadvances to block 1838 previously described. If the low/reverse pressureswitch 650 does equal one, the methodology advances to block 1852 andsets SLP 606 equal to neutral (See FIG. 5A). The methodology thenadvances to block 1838 previously described.

ACCELERATION CALCULATION

The purpose of the acceleration calculation is to control transmissionoperation during a shift or gear change. The acceleration calculationdetermines the actual acceleration of the turbine 128. This is a majorfactor in determining overall response of the control system.

Referring to FIG. 12, the calculated speed bubble 806 is illustrated. Atmost speeds, the speed calculation is made by counting the number ofteeth 319, 544 during a predetermined cycle and dividing that toothcount by the actual time elapsed between the first and last tooth. Timeis measured by counting clock cycles in the transmission controller3010. The tooth center lines are determined by reading a magnetic sensor320, 546 for the sixty-tooth input clutch retainer hub 312 for turbinespeed N_(t), and for the twenty-four-tooth second planet carrier 524 foroutput speed N_(o), respectively. At lower speeds, when no tooth passesduring the 7 millisecond (ms.) cycle, the update rate must be extendedto more than one predetermined cycle, i.e. 14 ms., 21 ms., etc., toprovide data down to the minimum speed needed.

Referring to FIG. 12, the calculated acceleration bubble 860 isillustrated. Acceleration is calculated by dividing the speed changebetween the last two measurements by the average of the two elapsedtimes. ##EQU1## N_(t) =calculated turbine r.p.m. N_(o) =calculatedoutput r.p.m.

alpha_(t) α_(t) =calculated turbine acceleration, r.p.m./sec.

n(i)=no. of teeth in latest count

n(i-1)=no. of teeth in previous count

T(i)=time required for n(i) teeth, seconds

T(i-1)=time required for n(i-1) teeth, etc.

For turbine speed N_(t) and acceleration alpha_(t), the calculationrange is from 40 to 6500 r.p.m. Acceleration must be calculated as soonas practical after reading turbine speed data because any time use slowsthe overall system response. For output speed N_(o), the calculationrange is from 40 to 6000 r.p.m. Due to problems with low speed dataintegrity, the maximum change for any update must be limited toplus/minus 30 r.p.m. when the previous output speed is less than 300r.p.m.

At low speeds (below about 1500 r.p.m.), an alternate method ofcalculating turbine acceleration is used. At higher speeds, however, therun-out inherent in the turbine speed wheel would generate a largefirst-order alternating acceleration term if this approach were used,thus interfering with good control.

To overcome this, a first-order filter is employed, which calculatesacceleration over an entire revolution. Speed is calculated based oneach quarter-revolution, the fourth previous speed (one revolutionbefore) is subtracted, and the difference is divided by the time for theone revolution. Because this acceleration calculation is more delayed,particularly at low speed, anticipation is necessary in order to achieveacceptable frequency response.

The following table defines the speed and acceleration calculations asfunctions of Ω, the number of quarter revolutions times. Ω=0 representslow speed operation. As the turbine accelerates, when 11 or more teeth(out of 60) pass in 7 ms., the switch to quarter revolution is initiatedand Ω begins to increment. After the fifth quarter revolution, onerevolution acceleration can be calculated; and after two more quarterrevolutions anticipation is effected. Low speed operation is resumedwhen more than 11.3 ms. is required for a quarter revolution.

    ______________________________________                                        Ω                                                                              N.sub.t    α.sup.(i)  α.sub.t                              ______________________________________                                        0      n(i)/T(i)                                                                                 ##STR1##        α.sup.(i)                            1      15/T(i)    "                "                                          2-4    "                                                                                         ##STR2##        "                                          5-6    "                                                                                         ##STR3##        "                                          7      "          "                αa                                   ______________________________________                                         where:                                                                        n(i) = no. of teeth in latest count (assuming 60tooth wheel)                  n(i - 1) = no. of teeth in previous count                                     T(i) = time required for n(i) teeth, seconds                                  T(i - 1) = time required for n(i - 1) teeth, etc.                             N.sub. t = calculated turbine r.p.m.                                          α.sup.(i) = calculated turbine acceleration, r.p.m./sec.                α.sub.t = turbine acceleration term for use in shift logic              αa = anticipated turbine acceleration, where                            αa = (1/4) * [(36-3B) * α.sup.(i) - (52-5B) *                     α.sup.(i-1) + (20-2B * α.sup.(i-2)                                α.sup.(i-1) = calculated accel. for previous quarter revolution,        etc.                                                                          B = INT [N.sub.t /512]; limit B ≧ 9                               

PRESSURE SWITCH TEST AND TRANSMISSION TEMPERATURE DETERMINATION METHOD

The purpose of the pressure switch test method is to verify that "OFF"element or clutch pressure switches will read high if a failure shouldoccur. The purpose of the transmission temperature determination methodis to determine when the transmission 100 has warmed up sufficiently toimpose normal response requirements when the transmission controller3010 sets the initial transmission temperature range (r) to either"warm" or "cold".

Referring to FIGS. 21A through 21C, the methodology for the pressureswitch test and transmission temperature determination is shown at 1900.At the beginning or start in block 1902, the methodology advances todiamond 1904 and determines whether the transmission 100 is presentlyoperating in first, second or third gear by performing speedcalculations. If the transmission 100 is not presently operating infirst, second or third gear, the methodology advances to diamond 1905and determines whether the shift lever position (SLP) 606 is reverse Ror neutral N by either the SLP or PRNODDL methods previously described.If SLP 606 is reverse or neutral, the methodology advances to block 1906and clears a retest flag. The methodology then advances to block 1907and turns OFF or terminates the pressure switch test. If SLP is notreverse or neutral, the methodology also advances to block 1907. Themethodology then advances to block 1908. At block 1908, the transmissioncontroller 3010 resets a timer to a predetermined value such as zero andsets a default value of time corresponding with three seconds if apressure switch test flag (PSTF) has been set or eleven seconds with thetransmission fluid temperature cold; five second with the transmissiontemperature fluid warm; and two seconds with the transmission fluidtemperature hot. Once this has been accomplished, the methodologyreturns.

At diamond 1904, if the transmission 100 is operating in either first,second or third gear, the methodology advances to diamond 1910 anddetermines whether the shift lever position (SLP) method or test,previously described, is ON or in progress by looking for a flag. If theSLP test is ON, or in progress, the methodology advances to block 1907previously described to terminate the pressure switch test. If the SLPtest is not ON, the methodology advances to diamond 1912 and determineswhether engine speed N_(e) is less than a predetermined speed, S, i.e.650 r.p.m. when the transmission fluid temperature is cold, or less than1000 r.p.m. when the transmission fluid temperature is warm or hot.Also, the transmission controller 3010 determines whether a N_(o) /N_(t)speed check fault count (SCF) is greater than a predetermined value or apressure switch fault count (PSF) is greater than another predeterminedvalue. If any of the above criteria is met in diamond 1912, themethodology advances to block 1907 previously described to terminate thepressure switch test. If all of the criteria is not met in diamond 1912,the methodology advances to block 1914 and starts or continues a timer.The methodology then advances to diamond 1916 and determines whether thepressure switch test is ON or in progress by looking for a flag. If thepressure switch test is not ON, the methodology advances to diamond 1918and determines whether the time on the timer is greater than apredetermined time period. If the time on the timer is not greater thanthe predetermined time period, the methodology returns. If the time onthe timer is greater than the predetermined time period, the methodologyadvances to diamond 1921 and determines whether SCF is less than apredetermined value such as 60 and the PSF equals zero. If that criteriais not true, the methodology advances to block 1908 previouslydescribed. If that criteria is true, the methodology advances to diamond1922 and determines whether a solenoid continuity test, to be describedunder section heading "SOLENOID CONTINUITY TEST METHOD", has beeninactive for a predetermined time period, i.e. greater than 400 ms, bylooking for a flag. If the solenoid continuity test has not beeninactive for the predetermined time period, the methodology returns. Ifthe solenoid continuity test has been inactive for more or greater thanthe predetermined time period, the methodology advances to block 1924.At block 1924, the transmission controller 3010 turns ON or activatesthe pressure switch test, sets count n on the counter equal to apredetermined value such as zero, and turns ON both the two/four shift634 and overdrive 632 solenoid-actuated valves. The methodology thenadvances to block 1926 and resets the timer equal to zero and sets adefault value corresponding to ten seconds with the transmission fluidtemperature cold; four seconds with the transmission fluid temperaturewarm; and sixty seconds with the transmission fluid temperature hot. Themethodology then returns.

If the pressure switch test is ON or activated at diamond 1916, themethodology advances to block 1927 and adds a value of 1 to the count non the counter such that n equals n plus 1. The methodology thenadvances to diamond 1928 (FIG. 21B) and determines whether thetransmission 100 is presently operating in first or second gear byperforming speed calculations and the OD pressure switch 646 is ON orpressurized. If that criteria is true, the methodology advances to block1930 and turns OFF the overdrive solenoid-actuated valve 632. Themethodology then advances to diamond 1932. If that criteria is not true,the methodology advances to diamond 1932 and determines whether thetransmission 100 is operating in first or third gear as previouslydescribed and the two/four shift pressure switch 648 is ON orpressurized. If that criteria is true, the methodology advances to block1934 and turns OFF the two/four shift solenoid-actuated valve 634. Themethodology then advances to diamond 1936. If that criteria is not true,the methodology advances to diamond 1936 and determines whether thetransmission temperature range is hot or the count n is greater than apredetermined value such as 7.

At diamond 1936, if the transmission fluid temperature is not hot or thecount n is not greater than 7, the methodology advances to diamond 1938and determines whether the two/four shift solenoid-actuated valve 634has been turned OFF. If the two/four shift solenoid-actuated valve 634is not OFF, the methodology returns. If the two/four solenoid-actuatedvalve 634 is OFF, the methodology advances to diamond 1940 anddetermines whether the engine temperature is greater than apredetermined temperature such as 75 degrees F. (Fahrenheit). If theengine temperature is greater than the predetermined temperature, themethodology advances to block 1942 and determines or concludes that thetransmission temperature range is warm. If the engine temperature is notgreater than the predetermined temperature, the methodology determinesor concludes that the transmission temperature range is still cold. Themethodology advances from block 1942 and diamond 1940 to diamond 1943and determines whether the count n is less than or equal to apredetermined value such as 5. If n is greater than 5, the methodologyadvances to diamond 1948 to be described. If n is less than or equal to5, the methodology advances to diamond 1944, which is initially set tozero, and determines whether a count x on a counter is greater than orequal to a predetermined value such as 8. If x is less than 8, themethodology advances to block 1945 and adds a predetermined value of 1to x such that x equals x plus 1. The methodology then advances todiamond 1948. If x is equal to or greater than the predetermined value,the methodology advances to diamond 1946 and determines if the enginetemperature is greater than a second predetermined temperature such as145 degrees F. If the engine temperature is greater than the secondpredetermined temperature, the methodology advances to block 1947 anddetermines or concludes that the transmission fluid temperature is hotand advances to diamond 1948. If the engine temperature is not greaterthan the second predetermined temperature, the transmission controller3010 maintains that the transmission fluid temperature is warm andadvances to diamond 1948.

If the transmission fluid temperature is hot at diamond 1936, themethodology advances to diamond 1948 and determines whether thetransmission 100 is operating in third gear and that the two/foursolenoid-actuated valve 634 has been turned OFF (i.e. at block 1934). Ifthat criteria is true, the methodology advances to block 1950 and clearsthe retest flag (RTF). The methodology then advances to block 1951 andturns OFF or terminates the pressure switch test and returns. If thecriteria in diamond 1948 is not true, the methodology advances todiamond 1952 and determines whether the transmission 100 is operating insecond gear and the overdrive solenoid-actuated valve 630 has beenturned OFF. If the above criteria is met or true at diamond 1952, themethodology advances to block 1950 previously described. If the abovecriteria is not met at diamond 1952, the methodology advances to diamond1954 and determines whether the transmission 100 is operating in firstgear and the two/four 634 and overdrive 630 solenoid-actuated valveshave been turned OFF. If that criteria is true, the methodology advancesto block 1950 previously described. If that criteria is not true, themethodology advances to diamond 1955 and determines whether the value ofn is greater than or equal to the value of Z. If n is less than Z, themethodology returns. If n is greater than or equal to Z, the methodologyadvances to diamond 1956 and determines whether the transmission fluidtemperature is cold. If the transmission fluid temperature is cold, themethodology advances to block 1951 previously described to terminate thepressure switch test. If the transmission fluid temperature is not cold,the methodology advances to diamond 1958 and determines whether theretest flag (RTF) has been set. If the RTF has been set, the methodologyadvances to block 1960 and reports a pressure switch test failure to thediagnostics to be described under section heading "ON-BOARDDIAGNOSTICS". The methodology then advances to bubble 1962 and goes toshutdown mode. If the RTF is not set, the methodology advances to block1964 and sets the RTF and the time on the timer equal to a predeterminedvalue such as 5. The methodology then advances to block 1951 previouslydescribed to terminate the pressure switch test and returns.

The preferred method of determining the fluid temperature of thetransmission 100 is an "accumulated run time" method. This methodpredicts T_(o), transmission fluid temperature. It bases the predictionon ambient and/or engine coolant temperatures and on observedtransmission and engine warm-up rates. By using ambient temperature, theengine block heaters use is accommodated. If engine temperature is lowerthan ambient, it will be used since it is more accurate. In the absenceof any temperature sensor data, -3° F. is used for ambient. The sensordata is received via the CCD link from the engine controller 3020.

This method includes measuring the time spent in a non-neutral gearcondition which represents effectively torque converter slippage. Whenthe torque converter 110 is slipping while transmitting torque from theengine to the transmission 100, heat is generated by energy conversion.This heat elevates the temperature of the transmission fluid. Thetransmission controller 3010 monitors time (T_(R)) (FIG. 21D) andapproximates with acceptable accuracy, the quantity of heat generated,and thereby the elevation of transmission fluid temperature. Testing canbe conducted to determine the relationship between the "run time" T_(R)and the quantity of temperature use (ΔT) in the transmission sump asillustrated in FIG. 21D.

The method includes reading the temperature of the engine by an inputsensor and multiplying the engine temperature by a predetermined valuesuch as 0.1. The method also includes reading the temperature of theambient air by an input sensor and multiplying the ambient temperature(T_(A)) by a predetermined value such as 0.9. These values are addedtogether to obtain the temperature point on the T_(o) ordinate. Thetransmission controller 3010 monitors or resumes the run time period(T_(R)) once the SLP 606 does not equal neutral N and N_(e) is greaterthan a predetermined speed such as 800 r.p.m. The measured run time ismultiplied by a predetermined slope value such as 10 and is added to thesummed value of the multiplied engine and ambient temperature. Thus, theequation of the curve T_(o) in FIG. 21D may be defined as follows:

    T.sub.o =(0.9T.sub.A +0.1 Σ)+10*T.sub.R

Accordingly, if T_(o) is less than 40° Fahrenheit (F.), the transmissionfluid temperature will be predicted or set to cold. If T_(o) is greaterthan 80° F., the transmission fluid temperature will be predicted or setto hot. Otherwise, the transmission fluid temperature is predicted as orset to warm.

Additionally, a transmission temperature flag β_(o) (super cold) allowsfor near-normal operation under sub-zero conditions. This flag is setwhen T_(o) is less than 0° F. and cleared when T_(o) is greater than 10°F. The super cold flag β_(o) is used by the transmission controller 3010to extend shift times and inhibit a third to first (3-1) shift bysetting a flag. Other uses are also available.

Accordingly, this alternative, but preferred method allows thetransmission controller 3010 to determine the transmission fluidtemperature without a dedicated temperature sensor immersed in thetransmission fluid.

SOLENOID CONTINUITY TEST METHOD

The purpose of the driver circuit continuity test is to check thesolenoid circuitry for proper operation. Since the solenoid drivercontrols the ground side of each solenoid coil 710 (FIG. 8), a directshort to ground in the line from the solenoid of the solenoid-actuatedvalves 630, 632, 634 and 636 to the transmission controller 3010 wouldenergize the solenoid coil 710 at a power level that can result inpermanent coil damage from overheating. An open circuit (or direct shortto supply voltage) would also prevent turning the solenoid-actuatedvalves "ON". Since these failures result in a loss of the normalinductive "OFF" spike (See FIG. 22E), a test which checks for thepresence of this spike is used to confirm circuit continuity.

The transmission controller 3010 of the present invention uses one spikemonitor circuit to test all the solenoids of the solenoid-actuatedvalves 630, 632, 634 and 636. The transmission controller 3010 uses aunique scheduling method or routine to ensure that the response of thespike monitor circuit is from the appropriate solenoid as shown by theblocks and diamonds enclosed by the dashed line of FIGS. 22B and 22C.When the torque converter 110 is either in unlock or pull-back, nosolenoids are under duty cycle control. The solenoids of thesolenoid-actuated valves are tested sequentially to guarantee the spikemonitor circuit response is from the appropriate solenoid.

When the torque converter 110 is in partial lock-up, the low/reverseclutch solenoid-actuated valve 636 is under duty cycle (interrup)control. The low/reverse clutch solenoid-actuated valve 636 is tested bylooking for the spike monitor circuit response caused by normal turn OFF(de-energizing) via the interrupt control. The remaining solenoids arethen tested in sequence.

If the low/reverse clutch solenoid is ON (energized), a low/reverseinterrupt is disabled to guarantee the spike monitor circuit response isfrom the solenoid under test and not from the low/reverse solenoid whichis under interrupt control. If the low/reverse clutch solenoid is OFF, alow/reverse recirculation driver is turned ON to make sure the spikemonitor circuit has recovered from the spike caused by the last turn OFFof the low/reverse clutch solenoid via the interrupt. This method ortechnique guarantees that the response of the spike monitor circuit isfrom the appropriate solenoid.

Referring to FIGS. 22A through 22D, the methodology for the solenoidcontinuity test is shown. At the beginning, in bubble 2000, themethodology advances to diamond 2002 and determines whether the solenoidcontinuity test is in progress by looking for a flag. If the solenoidcontinuity test is not in progress, the methodology advances to diamond2004 and determines whether it is time to run the solenoid continuitytest by looking for a flag for example. If it is not time to run thesolenoid continuity test, the methodology returns. If it is time to runthe solenoid continuity test, the methodology advances to diamond 2006and determines whether a shift is in progress by looking for a flag. Ifa shift is in progress, the methodology returns. If a shift is not inprogress, the methodology advances to diamond 2008 and determineswhether the shift lever position (SLP) test, previously described, is inprogress by looking for a flag. If the SLP test is in progress, themethodology returns. If the SLP test is not in progress, the methodologyadvances to diamond 2010 and determines whether the pressure switch(P/SW) test, previously described, is in progress by looking for a flag.If the P/SW test is in progress, the methodology returns. If the P/SWtest is not in progress, the methodology advances to block 2012 and setsa "solenoid test in progress flag", "turn solenoid ON" flag, and a"low/reverse LR solenoid under test" flag and returns. The abovemethodology is used because a solenoid continuity test sequence cannotoccur while a shift, shift lever position test or pressure switch testis in progress.

At diamond 2002, the transmission controller 3010 determines whether thesolenoid continuity test is in progress as previously described. If thesolenoid continuity test is in progress, the methodology advances todiamond 2014 and determines whether a SLP test is in progress aspreviously described. If a shift lever position test in in progress, themethodology advances to block 2016 and aborts the test sequence byclearing the "solenoid test in progress" flag and advances to block2018. At block 2018, the transmission controller 3010 outputs the normalin-gear solenoid mask (i.e. logical states) to the solenoid-actuatedvalves and returns. If the SLP test is not in progress at diamond 2014,the methodology advances to diamond 2020 and determines whether a shiftis in progress as previously described. If a shift is in progress, themethodology advances to block 2016 previously described. The abovemethodology is used to interrupt the test sequence for a shift leverposition test or a shift in progress.

If a shift is not in progress, the methodology advances to diamond 2022and determines whether the low/reverse solenoid-actuated valve 636 isunder test by looking for a flag for example. In the test sequence, eachsolenoid-actuated valve must be tested separately to ensure that theresponse is from the appropriate solenoid. Therefore, if the low/reversesolenoid-actuated valve 636 is not under test, the methodology advancesto diamond 2024 and determines whether it is time to turn ON thesolenoid under test by looking for a flag for example. If it is time toturn ON the solenoid under test, the methodology advances to block 2026and turns ON the solenoid under test, clears the "turn solenoid ON"flag, and clears the "in partial lock-up (PL) last loop" flag andreturns. If it is not time to turn ON the solenoid under test, themethodology advances to diamond 2054 to be described.

At diamond 2022, the transmission controller 3010 determines whether thelow/reverse solenoid-actuated valve 636 is under test by looking for aflag for example. If the low/reverse solenoid-actuated valve 636 isunder test, the methodology advances to diamond 2028 and determineswhether partial lock-up of the torque converter 110 is in progress bylooking for a flag. If partial lock-up is not in progress, themethodology advances to diamond 2024 previously described. If partiallock-up is in progress, the methodology advances to diamond 2030 anddetermines whether it is time to turn ON the solenoid-actuated valveunder test as previously described. If it is time to turn ON thesolenoid-actuated valve under test, the methodology advances to diamond2031 and determines whether the methodology is at the start of a partiallock-up period, previously described (FIG. 18B), by looking for a flagfor example. If the methodology is at the start of a partial lock-upperiod, the methodology returns. If the methodology is not at the startof a partial lock-up period, the methodology advances to block 2032 andclears a "spike monitor edge detect" flag, a "spike response" flag, a"turn ON solenoid" flag, and "first partial lock-up period has elapsed"flag. The methodology then advances to block 2033 and sets a "in partiallock-up last loop" flag. The methodology then returns.

At diamond 2030, if it is not time to turn ON the solenoid-actuatedvalve under test, the methodology advances to diamond 2034 anddetermines whether partial lock-up of the torque converter 110 occurredin the last loop by looking for a flag. If partial lock-up did not occurin the last loop, the methodology advances to block 2035 and sets the"turn ON solenoid" flag. The methodology then advances to block 2036 andoutputs a normal in-gear solenoid mask as previously described. Themethodology then returns.

If partial lock-up occurred in the last loop at diamond 2034, themethodology advances to diamond 2037 and determines whether a "spikeresponse" previously described was received from the low/reverseinterrupt. If a spike response was not received, the methodologyadvances to diamond 2038 and determines whether the partial lock-upperiod has expired by looking for a flag for example. If the period hasnot expired, the methodology advances to block 2036 previouslydescribed. If the period has expired, the methodology advances todiamond 2040 and determines whether the "first partial lock-up periodhas elapsed flag" has been set. If the flag has not been set, themethodology advances to block 2042 and sets the "first partial lock-upperiod has elapsed" flag. The methodology then advances to block 2036previously described. If the flag has been set, the methodology advancesto diamond 2048 to be described herein.

At diamond 2037, if a spike response was not received, the methodologyadvances to block 2044 and points to the next solenoid-actuated valve tobe tested. The methodology then advances to block 2046 and sets the"turn solenoid ON" flag. The methodology then advances to block 2047 andoutputs the normal in-gear solenoid mask for the solenoid-actuatedvalves as previously described. The methodology then returns.

At diamond 2040, if the "first partial lock-up period has elapsed flag"has been set, the methodology advances to diamond 2048 and determineswhether a second failure has occurred by looking for a flag for example.If a second failure has occurred, the methodology advances to block 2050and notifies the diagnostics, to be described, of the transmissioncontroller 3010 and advances to shut down mode. If a second failure hasnot occurred, the methodology advances to block 2052 and sets a "firsttest failed" flag, sets a "shift inhibit" flag, clears the "solenoidtest in progress" flag, and reschedules the next test sequence, in apredetermined time period, i.e. 2 seconds. The methodology then advancesto block 2047 previously described.

At diamond 2054, the transmission controller 3010 determines whether thelow/reverse solenoid-actuated valve 636 is under test as previouslydescribed. If the low/reverse solenoid-actuated valve 636 is under test,the methodology advances to diamond 2056 and determines whether partiallock-up of the torque converter 110 occurred in the last loop by lookingfor a flag. If partial lock-up occurred in the last loop, themethodology advances to block 2058 and sets the "turn solenoid ON" flag.The methodology advances to block 2059 and outputs the normal in-gearsolenoid mask as previously described and returns.

If the low/reverse solenoid-actuated valve 636 is not under test orpartial lock-up did not occur in the last loop, the methodology advancesto diamond 2060 and determines whether the low/reverse solenoid-actuatedvalve 636 is ON as previously described. If the low/reversesolenoid-actuated valve 636 is not ON, the methodology advances to block2062 and turns ON the LR/LU recirculation driver to guarantee that thespike monitor circuit has recovered. The methodology advances to block2064 and delays for a predetermined time period (T₂). The methodologythen advances to block 2068 to be described herein.

At diamond 2060, if the low/reverse solenoid-actuated valve 636 is ON,the methodology advances to diamond 2065 and determines whether theLR/LU interrupt is enabled by looking for a flag for example. If theLR/LU interrupt is enabled, the methodology advances to block 2066 anddisables the LR/LU interrupt. The methodology then advances to block2068. If the LR/LU interrupt is not enabled, the methodology advances todiamond 2068 and clears the "spike monitor edge detect" flag. Themethodology then advances to block 2070 and turns OFF thesolenoid-actuated valve under test. The methodology then advances todiamond 2072 and determines whether the spike monitor circuit hasresponded by looking for a back EMF spike when the solenoid is turnedOFF. If the spike monitor circuit has responded, the methodologyadvances to block 2074 and sets a "spike response" flag. If the spikemonitor circuit has not responded, the methodology advances to diamond2076 and determines whether the predetermined time period (T₂) hasexpired by looking at a timer for example. If the predetermined timeperiod has not expired, the methodology loops back to diamond 2072previously described. If the predetermined time period has expired, themethodology advances to block 2078 and clears the "spike response" flag.

From blocks 2074 and 2078, the methodology advances to block 2080 andrestores the LR/LU recirculation driver and LR/LU interrupt to theiroriginal state. The methodology then advances to diamond 2082 anddetermines whether the "spike response" flag has previously been set. Ifthe spike response flag has not been set, the methodology advances todiamond 2048 previously described. If the spike response flag has beenset, the methodology advances to diamond 2084 and determines whether allfour solenoid-actuated valves 630, 632, 634 and 636 have been tested bylooking to see if four spikes have been received. If all foursolenoid-actuated valves have been tested, the methodology advances toblock 2086. At block 2086, the transmission controller 3010 clears the"shift inhibit" flag, clears the "first test failed" flag, clears the"solenoid in progress" flag, and reschedules the next test sequence in apredetermined time period such as 10 seconds. The methodology advancesto block 2047 previously described.

THROTTLE ANGLE COMPUTATION AND FAILURE DETECTION

The purpose of the throttle angle computation and failure detectionmethod is to compute the throttle angle and to detect any failures ofthe throttle pot and associated circuitry as described in U.S. Pat. No.4,637,361, issued January 20, 1987, in the name of Killen, et. al.,which is hereby incorporated by reference. The throttle angle value isused in circle 814 and 854 of FIG. 12 for the shift schedule method(FIG. 14). This parameter must be checked and upon detecting a failure,a default throttle value is used to ensure satisfactory operation.

Referring to FIGS. 23A and 23B, the methodology for the throttle anglecomputation is shown. The methodology starts in bubble 2100 and thenadvances to diamond 2102. At diamond 2102, the transmission controller3010 determines whether the raw throttle angle data (THR_(D)) from thethrottle pot is greater than or equal to a predetermined value such aseight degrees (See FIG. 23C). If that criteria is not true, themethodology advances to block 2156 to be described. If that criteria istrue, the methodology advances to diamond 2104 and determines whether ashift is in progress by looking for a flag which is set when the shiftbegins. If a shift is in progress, the methodology advances to block2106 to be described herein.

If the shift is not in progress, the methodology advances to diamond2108 to determine whether the raw throttle angle data (THR_(D)) is lessthan or equal to the closed minimum throttle value (THR_(o)) of thethrottle data minus a predetermined value such as 1/2 (0.5) degrees (SeeFIG. 23C). If that criteria is true, the methodology advances to block2110 and increments a minimum throttle counter such as a timer in themethodology. The methodology then advances to diamond 2112 to determinewhether the minimum throttle counter is equal to a predetermined valuesuch as six counts. If that criteria is not true, the methodologyadvances to diamond 2114 to be described herein. If that criteria istrue, the methodology advances to block 2116 and decrements the closedminimum throttle value (THR_(o)) of the raw throttle angle data(THR_(D)). The methodology advances to diamond 2118 to be describedherein.

At diamond 2108, if the raw throttle angle data is greater than theclosed minimum throttle value minus a predetermined value such as 1/2(0.5) degrees, the methodology advances to diamond 2120. At diamond2120, the transmission controller 3010 determines whether the throttleangle at update (THR) is greater than or equal to a predetermined valuesuch as 1/2 degree (See FIG. 23C). If that criteria is not true, themethodology advances to block 2106 to reset the minimum throttlecounter. If that criteria is true, the methodology advances to diamond2122 and determines whether output speed N_(o) is less than apredetermined value such as 200 r.p.m. If the output speed N_(o) is lessthan the predetermined value, the methodology advances to diamond 2124and determines whether engine speed N_(e) is greater than apredetermined value such as 400 r.p.m. but less than a maximumpredetermined value such as N_(e) (maximum engine speed) plus a valuesuch as 50 r.p.m. If that criteria is true, the methodology advances toblock 2130 to be described. If N_(o) is not less than 200 r.p.m. orN_(e) is not greater than 400 r.p.m., or N_(e) is not less than N_(e)plus 50 r.p.m., the methodology advances to diamond 2126 and determineswhether the PRNODDL code from the contact switch sensors NS₁ and NS₂equals drive. If the PRNODDL code does not equal drive, the methodologyadvances to block 2106 previously described. If the PRNODDL code doesequal drive, the methodology advances to diamond 2128 and determineswhether engine speed N_(e) is less than turbine speed N_(t) minus apredetermined value such as 50 r.p.m. If that criteria is not true, themethodology advances to block 2106 previously described. If thatcriteria is true, the methodology advances to block 2130 and incrementsthe minimum throttle counter. The methodology advances to diamond 2132and determines whether the minimum throttle counter equals apredetermined value such as 28. If that criteria is not true, themethodology advances to diamond 2114 to be described herein. If thatcriteria is true, the methodology advances to block 2134 and incrementsthe closed minimum throttle value of raw throttle angle data andadvances to diamond 2118.

At diamond 2118, the transmission controller 3010 determines whether theclosed minimum throttle value is greater than or equal to a minimumpredetermined value such as eight degrees, but less than or equal to amaximum predetermined value such as forty-eight degrees. If thatcriteria is true, the methodology advances to block 2106 previouslydescribed. If that criteria is not true, the methodology advances toblock 2136 and limits the closed minimum throttle value. The methodologythen advances to block 2106 previously described to reset the minimumthrottle counter. The methodology then advances to diamond 2114.

At diamond 2114, the transmission controller 3010 determines whether theraw throttle angle data is greater than the closed minimum throttlevalue. If that criteria is not true, the methodology advances to block2138 and sets a new unlimited throttle angle equal to a predeterminedvalue such as zero. The methodology then advances to block 2140 to bedescribed herein.

At diamond 2114, if the throttle data is greater than the closed minimumthrottle value, the methodology advances to diamond 2142 and determineswhether the new unlimited throttle angle is less than or equal to apredetermined value such as 100 degrees. If that criteria is not true,the methodology advances to block 2156. If that criteria is true, themethodology advances to block 2140 and updates the minimum throttleangle memory location with THR_(o) just computed. The methodology thenadvances to diamond 2144 (See FIG. 23B) and determines whether thechange in the new unlimited throttle angle (ΔTHR) is between apredetermined range such as -5 to 5 degrees. If that criteria is nottrue, the methodology advances to block 2146 and sets the change inthrottle angle within a predetermined limit such as ±5 degrees. Themethodology then advances to block 2147 and sets the delta (Δ) throttleexceeded limit flag (DTHFLG) equal to one. The methodology then advancesto block 2148 to be described herein.

At diamond 2144, if the change in the new unlimited throttle angle isbetween the predetermined range, the methodology advances to block 2145and clears the delta throttle exceeded limit flag (set equal to zero).From block 2145, the methodology advances to block 2148 and calculates anew throttle angle based on the old throttle angle at update plus thechange in throttle angle. The methodology advances to diamond 2150 anddetermines whether the throttle error counter (ψ) is greater than apredetermined value such as 192 counts. If this criteria is true, themethodology advances to block 2154 to be described. If that criteria isnot true, the methodology advances to block 2152 and sets the throttleangle at update equal to the new throttle angle because normal operationof the hardware is occurring. The methodology advances to diamond 2154and determines whether the delta (Δ) throttle exceeded limit flag haspreviously been set. If that criteria is true, the methodology thenadvances to block 2156 and increments the throttle error counter. Themethodology advances to diamond 2158 and determines whether the throttleerror counter is greater than or equal to a predetermined value such as255. If that criteria is true, the methodology advances to block 2160and sets the throttle error counter to this predetermined value andreports a failure to the diagnostics providing that engine speed N_(e)is greater than a predetermined value such as 500 r.p.m. and the rawthrottle angle data (THR_(D)) is less than a predetermined value such as6° or greater than a predetermined value such as 120.5°. The methodologythen returns. If the throttle error counter is less than thepredetermined value, the methodology advances to diamond 2162.

At diamond 2154, if the delta throttle exceeded limit flag has notpreviously been set, the methodology advances to diamond 2164 todetermine whether the throttle error counter is equal to a predeterminedvalue such as zero. If the throttle error counter equals zero, themethodology returns. If the throttle error counter does not equal zero,(i.e. an error has occurred), the methodology advances to block 2166 anddecrements the throttle error counter. The methodology advances todiamond 2162 to determine whether the throttle error counter is greaterthan a predetermined value such as 192. If that criteria is not true,the methodology returns. If that criteria is true, the methodologyadvances to block 2168 and sets the throttle angle data equal to apredetermined value such as 25 degrees (default value) and inhibitslock-up operation of the torque converter, previously described, bysetting a flag for example. From block 2168, the methodology returns.

SHIFT METHODOLOGY

The present invention provides fully adaptive electronic transmissioncontrols. These adaptive controls perform their functions on real-timefeedback sensor information, as is likewise performed by electronicantiskid brake controls. Additionally, the adaptive controls "learn"particular information by monitoring data such as the value for the filltime and apply rate of the applying element such as a clutch. Thisinformation is then stored in the memory of the transmission controller3010 for future use.

UPSHIFT METHODOLOGY

The upshift methodology uses the learned values for the fill time andapply rate (torque build-up rate) of the ON-coming or applying elementsuch as a clutch and for the release time of the OFF-going or releasingelement such as a clutch. Learning apply element fill time permitstiming the beginning-of-fill so as to compensate for orifice size orclutch clearance variations, etc. Learning the apply rate and releasetime allows compensation for variations in orifice size, clutchcapacity, solenoid response, and torque requirement (included to someextend, different engines). Although learning is restricted to the HOTmode, some temperature compensation occurs between summer and winter.

In the power-ON upshift, the methodology adjusts the apply and releaseevents so that release element slip occurs just before the apply elementbegins to develop torque. Slip must be allowed to occur so that therelease and apply events can be identified by speed measurements. Insimplified terms, release time is measured as the interval betweeninitial-element-vent and beginning-of-slip; fill time is frombeginning-of-fill to end-of-bump-along; and apply rate is fromend-of-bump-along to beginning-of-speedchange. Bump-along is a termcoined to describe the bang-bang (fixed percent ON-OFF time) controlperiod that the methodology uses to maintain a small amount of backwardslip prior to the application of the apply element. The methodologydelays either the beginning of the release vent or the beginning ofapply fill so as to achieve approximately one cycle of bump-along.

This control methodology reduces the release element pressure to theminimum that will still support the input torque reaction, therebyestablishing the optimum beginning conditions for the element exchange.The apply rate, then, is selected to develop the torque needed to beginspeed change just as release element net-apply-pressure reaches zero.Thus, the duty-cycle-controlled apply rate matches the ballistic releaserate of the OFF-going or releasing element. The purpose of the matchedexchange, of course, is to minimize fight between the elements. Releasetime and apply rate are both learned relative to the throttle angle.

Once the speed change begins, the apply element pressure is controlledto provide the desired turbine acceleration alpha_(t). This speed changecontrol is the heart of adaptive control since it adapts to changes inengine torque, friction coefficient, etc. and provides consistentcontrol.

The acceptability of the power-OFF upshift must be verified with theappropriate engine control methodology. With carburetors, the enginespeed N_(e) drops quickly and may pull the turbine 128 through the speedchange faster than desired. This can result in both elements going orstaying off, which, if the throttle is opened, will result in a runawaybump as both elements race to apply. In order to prevent this,methodolgy was devised which uses both elements to control the speedchange and gradually accomplish the hand-off. With the electronic enginecontrol, the engine may vary between power-ON and power-OFF. It may evenprovide the correct programmed rate past the target speed (N_(t) =N_(j))without either element controlling, thus defeating the above approach.Methodology has been added which simply turns ON the apply element whenthe speed change is complete. Also, with this shift, it is desirable torelease the OFF-going element quickly to avoid excessive engine brakingtorque.

The learned term for fill time is time remaining to nearly fill, T_(f).Using T_(f) minimizes the possibility of a too aggressive elementapplication and allows the use of a duty cycle to soften the initialapplication. T_(f) is actually calculated from the learned clutch fillvolume, V_(f). This term is stored in cubic inches so that differentflow rates may be used to calculate T_(f). This allows the same learnedvolume to be used for different shifts which may have a different linepressure. The program or methodology continually tracks the fluid volumeneeded to apply each element.

The learned term for release time, above, is time to nearly release,T_(r), which is calculated as K_(s) * T_(s) -0.063. T_(s) is a tablevalue for the nominal observed release time. K_(S) is the learnedmultiplier for that individual package. Since T_(s) varies with THR(i.e. engine torque), a multiplier provides the best data match for thevariables being accommodated. The 0.063 seconds, together with the T_(f)differential, provides a margin to ensure that fight is minimized.

KICKDOWN METHODOLOGY

For good kickdown feel, it is essential that the shift occur quickly.The use of accumulators delays the clutch or element release so everyeffort is made to minimize the accumulator fill/vent times. Themethodology turns OFF the release element at the start of the shift anddoes not apply it again until turbine acceleration exceeds a desiredlevel by a small amount. A duty cycle (DC) may then be initialized andupdated to provide proportional control for the speed change. Theprimary element DC acceleration or proportional control (DC_(alpha),i.e. variable percent ON or OFF time) initialization level is calculatedfor N_(e) and N_(t), the torque converter characteristics, and theelement capacity; each DC_(alpha) update is based on an anticipatedturbine acceleration (alpha_(t)) error.

As illustrated in FIG. 24A, a shift tape of the transmissioncharacteristics for a third to first (3-1) kickdown shift is generallyshown at 2200. Curve 2202 represents throttle angle. As throttle angleincreases, engine speed N_(e) shown in curve 2204 also increases.Simultaneously, the release element is released as shown in curve 2206to drop its torque capacity. In other words, for a third to first (3-1)gear kickdown shift, the overdrive clutch 304 is released at the startof the shift. As shown by curve 2208, the fluid pressure of theoverdrive clutch 304 vents down. When the torque capacity of theoverdrive clutch 304 is low enough (at the fill volume), the turbine 128will breakaway and a speed change will start as indicated by numeral2210.

The present invention limits the rate at which the turbine 128accelerates. This is accomplished by calculating and comparing aninstantaneous turbine acceleration (alpha_(t)) shown in curve 2212against a desired acceleration (alpha_(desired) or α*) level shown incurve 2214. Once the speed change begins at 2210, the controller 3010attempts to match alpha_(t) approximately equal with alpha_(desired).

When alpha_(t) exceeds alpha_(desired), the release element is reappliedto control the rate at which the turbine 128 accelerates. The releaseelement is reapplied under duty cycle acceleration or proportionalcontrol (DC_(alpha)) to provide a controlled slope of speed change onthe turbine 128.

As illustrated in FIG. 24A, curve 2212 of alpha_(t) crosses curve 2214of alpha_(desired) at point 2216. At point 2216, the overdrive clutch304 is reapplied by duty cycling the solenoid-actuated valve 632 asshown by part 2218 of curve 2206.

Simultaneously with speed change, the kickdown methodology adaptivelyapplies the applying element (low/reverse clutch 310) as shown by curve2220 based on the remaining turbine speed change which has to occur. Asturbine speed N_(t) increases in curve 2222, the methodology comparesthe actual turbine speed N_(t) to a target speed N_(j) (for a 3-1 shift,first gear ratio of first gear N_(j)). Because the speed change is madeat a known rate (because controlling release element at that rate), themethodology can predict how much time remains to fill the applyingelement. The methodology attempts to get the applying element filledafter achieving the target speed N_(j) for a predetermined time periodsuch as 120 ms, which region 2224 of curve 2214 is called "hold-speed".

When N_(t) exceeds the target speed N_(j) at point 2226, i.e. enters thehold-speed region 2224, alpha_(desired) is lowered again to a negativevalue at point 2228 on curve 2214 so that the release element willprevent further increases in N_(t). DC_(bb) is again used for improvedresponse before reentering DC_(alpha) control. The release elementhold-speed continues until the apply element is filled, begins todevelop torque, and pulls N_(t) down to the target level, N_(j). Themethodology then turns OFF the release element when N_(t) equals N_(j).

To reduce the energy (and provide a faster shift), learning is used tolimit the hold-speed period to the minimum that will accomplish the"apply" identification and improve "shift feel". To know whether to turnON the apply element (i.e. cause the solenoid to apply), the methodologystarts which a "hold-speed" time allowance and adds to that atime-to-complete-speed-change, which is calculated by (N_(j)-N_(t))/alpha_(desired). This "time available (from now until theelement should apply)", is continuously compared to the "time required(element volume divided by fill rate)" and the solenoid-actuated valveis turned ON or OFF as required. Since the methodology tracks elementvolume during solenoid OFF and ON times, there is little error that candevelop if alpha_(t) is lower than alpha_(desired). When alpha_(t) islow and the actual N_(t) becomes lower than projected, the methodologysimply turns OFF the element and waits for N_(t) to catch up to theprojected level. If alpha_(t) is higher than alpha_(desired), thecontrols have no means to catch up, but since the initial releaseelement vent time and the alpha_(desired) "feather" control causealpha_(t) to be lower than alpha_(desired) normal, there is noopportunity for significant "fall-behind" error to develop.

To achieve 120 ms. of hold-speed, the present invention utilizes"adaptive" kickdown start logic which is based on a "learned" fillvolume of the applying element. The equation for the kickdown startlogic may be defined as follows:

    N.sub.t >N.sub.j -S,

where S=alpha_(desired) * t_(f) =r.p.m. S is the kickdown start value(r.p.m. of turbine remaining) which equals t_(f) multiplied byalpha_(desired). As illustrated in FIG. 24A, curve 2232 represents thekickdown start value S. t_(f) is the time needed to fill the applyingelement to the level that will provide the correct amount of bump-alongtime or kickdown hold-speed time (i.e. 120 ms). It is continuouslyupdated and includes compensation for any expected duty cycle use duringthe remaining fill time. t_(f) is calculated as follows: ##EQU2## K_(f)=DC COMPENSATION FACTOR: Corrects for the reduced fill rate when DC useis expected. K_(f) =1 for kickdown shift

V_(f) =fill volume of the applying element

Q_(f) =flow rate of the applying element

M=correction factor for line pressure

V=instantaneous element volume

Since N_(j) is the ratio multiplied by N_(i), N_(t) can be controlled ata desired slope by the release element so that N_(t) goes to N_(j)during t_(f), having 120 ms of hold-speed to completely fill the applyelement. t_(f) is continuously calculated to give the kickdown startvalue S. Whenever N_(t) crosses S (i.e. N_(t) >N_(j) -S), the applyelement is turned ON which reduces S because the apply element isfilling. If N_(j) -S>N_(t) (i.e. N_(t) falls below S), the apply elementis turned OFF. This results in an irregular or variable DC on the applyelement. In other words, once the kickdown start value S is calculated,the transmission controller 3010 compares N_(t) to S. If N_(t) isgreater than N_(j) minus S, the methodology instructs the transmissioncontroller 3010 to turn ON the applying element to reduce S to zero.Hence, the methodology drives S to equal zero just as N_(t) crosses orequals N_(j) at point 2226. This allows 120 ms. of time remaining tocomplete the fill (hold-speed), resulting in better shift quality.Otherwise, the shift quality would be "jerky" if the apply element wereapplied just as N_(t) crossed N_(j).

TURBINE TORQUE CALCULATION

Referring to FIG. 24A, until alpha_(t) crosses alpha_(desired) for thefirst time at point 2216, the release element is held completely OFF sothat any initial speed change is not delayed. Once the speed change iscomplete at point 2228, it is desired not to overshoot alpha_(desired).Therefore, a duty cycle is calculated that will hold or maintainalpha_(desired). The turbine torque calculation is used to calculate theinitial percent ON time, indicated at 2216, for the duty cycle (DC) ofthe release element.

The initial percent ON time of the release element for either adownshift or garage shift is calculated as follows:

    Initial % ON=DC.sub.o +(T.sub.t -I.sub.t * alpha.sub.desired)/K.sub.t

whereby,

DC_(o) =Zero torque DC estimate

I_(t) =Equivalent turbine inertia

K_(t) =Gain, DC to turbine torque (T_(t))

In the above equation, DC_(o) is the duty cycle needed to maintain fillpressure on the release element, which is predetermined value. I_(t)×α_(desired) is the net torque to maintain desired acceleration which isalso a predetermined value. K_(t) is the gain from the DC to the turbinetorque which is a predetermined value. DC_(o), I_(t) and K_(t) vary forthe shift involved, i.e. fourth to third gear, fourth to second gear,etc. The equation for turbine torque (T_(t)) is defined below: ##EQU3##

As illustrated in FIG. 24B, the equation for the turbine torque (T_(t))is derived by the graph of turbine torque T_(t) divided by engine speedN_(e) squared (which is the same as impeller speed squared) versus speedratio of turbine speed N_(t) divided by engine speed N_(e) which iscurve 2280. For turbine speed N_(t) less than a predetermined constantK₃ times engine speed N_(e), the equation for turbine torque T_(t) isindicated by part 2282 of curve 2280. For turbine speed N_(t) equal toor greater than K₂ multiplied by N_(e), the equation for turbine torqueT_(t) is indicated by part 2284 of curve 2280.

FIG. 24B is based on the characteristics of a particular model of torqueconverter. This can be used at any time that the lockup clutch isdisengaged to calculate an input torque to the transmission 100. For aparticular element involved (knowing what its capacity is), thetransmission controller 3010 can calculate the DC necessary to providethe appropriate level of element torque (i.e. initial DC). After theinitial percent ON time for the DC, the DC adaptively adjusts tomaintain alpha_(desired).

LEARN METHODOLOGY

The only learned quantity used for making downshifts is the fill time ofthe applying element or clutch. As previously mentioned, the elementvolumes are actually learned and stored. Fill times are calculated byusing the learned element volume and an appropriate flow rate from alook-up table and graph of flow rate characteristics for each elementfor example. The learned volume information for a given element isshared between different shifts, both upshifts and downshifts. The flowrate used accounts for the individual hydraulic flow rates andcompensates for line pressure differences which exist between differentshifts (i.e. for element fill rates, not vent rates).

With a coastdown shift, however, the pump 200 will not, under allconditions, have the capacity to maintain the regulated line pressure.To compensate for the resulting low line pressure, a learned fill rateis used for coastdown shifts only. This fill rate is set at theregulated line pressure level with each start-up (because with coldfluid, the pump 200 will maintain the regulated pressure) and it willlearn any reduction in the fill rate with each subsequent shift.

Learning fill time with downshifts is similar to upshifts in that thebeginning of apply (end of fill time for the apply element) isidentified by the ending of a "hold-speed" control maintained by therelease element in power-ON shifts. Implicit with this is the necessityof establishing some "hold-speed" control rather than timing an exactapplication to be described herein. It is also necessary to handle OFFand ON times correctly since the fill event is seldom a continuous ON;the flow rates, mentioned above, provide this capability.

The learn logic for kickdown shifts tracts the instantaneous volume ofthe apply element and compares that value with the current fill volumesuch that the apply element is completely filled at the end of thehold-speed region.

As illustrated in FIG. 24C, curve 2250 represents a desired acceleration(α*) of the turbine 128. Curve 2252 represents turbine speed N_(t) andcurve 2254 represents a target speed (N_(j)) of the turbine 128. Curve2256 represents an instantaneous fill volume (V_(I)) of the applyelement and curve 2258 represents the current fill volume (V_(f)) of theapply element. As N_(t) approaches N_(j), N_(t) comes within apredetermined range 2260 of N_(j). At point 2263 when N_(t) reaches thelower limit of the predetermined range 2260, the learned volume (V_(L))of the apply element is latched at that volume of the instantaneous fillvolume (V_(I)). Once N_(t) leaves the upper limit of the predeterminedrange 2260 at point 2264, the learned volume again tracks theinstantaneous fill volume until N_(t) enters the predetermined region2260 at point 2266. At point 2266, the learned volume of the applyelement is latched at that value of the instantaneous fill volume. Atthe end of the shift (EOS), the transmission controller 3010 takes astep out of current fill volume (V_(f)) which is a percentage of thedifference between V_(f) and V_(L) at point 2266.

The fill volume (V_(f)) of the apply element is also "learned" andadaptively adjusted based on bump-along (i.e. element slip). Asillustrated in FIG. 24D, a shift tape of the transmissioncharacteristics is shown for a first to second (1-2) upshift. Curve 2270represents the stored or previously learned current fill volume (V_(f))of the apply element. Curve 2272 represents the instantaneous volume(V_(I)) of the apply element (i.e. two/four shift clutch 308). Curve2274 represents the learned volume (V_(L)).

While a shift is in progress, the learned volume (V_(L)) is set equal tothe instantaneous fill volume (V_(I)) whenever (t_(f) >0) or (t_(f) ≠0and N_(f) >N_(j) +30). As shown in FIG. 24D, V_(L) tracts V_(I) untilpoint 2274 because t_(f) was greater than 0. At point 2276, t_(f) equalszero and V_(L) stops tracking V and is set equal to the value of V_(I)at point 2276. When t_(f) =0, the apply element is filling in thehold-speed region. If N_(t) is greater than N_(i) plus a predeterminedvalue such as 30 (i.e. slip occurs), called bump-along, V_(L) is updatedto the value of V_(I) at point 2278. At point 2278, V_(L) again tracksV_(I) until N_(t) is not greater than N_(i) plus the predetermined valueat point 2280. At point 2280, V_(L) is set equal to the value of V_(I)and stops tracking. This methodology is repeated whenever N_(t) isgreater than N_(i) plus the predetermined value. At the end of theshift, the transmission controller 3010 compares V_(L) to V_(f). IfV_(L) is greater than V_(f), as shown in FIG. 24D, V_(f) is adjusted orincreased a percentage of difference between V_(L) and V_(f). If V_(L)equals V_(f), no adjustment is made. Otherwise, if V_(L) is less thanV_(f), V_(f) is decreased.

Referring to FIG. 24E, a flow chart of the learn methodology is shown.At the start of the methodology in bubble 2290, the methodology advancesto block 2292. At block 2292, the methodology intercepts or determinesthe time to bump-along, time to speed change, and instantaneous volumeduring bump-along of the element. The methodology then advances todiamond 2294 and determines whether the shift has been completed. If no,the methodology loops back to block 2292. If the shift has beencompleted, the methodology advances to block 2296 and learns the fillvolume if the conditions are valid, learns K_(s) (release timemultiplier), if conditions are valid and learns DC_(t) (adjustment) ifconditions are valid. From block 2186, the methodology returns.

COASTDOWN METHODOLOGY

The shift schedule (bubble 810 of FIG. 12) has logic which comparesengine speed N_(e) and target speed N_(j) and delays any coastdown shiftthat would go from power-ON to power-OFF since these shifts involvecrossing drivetrain backlash and may result in a "clunk". The 3-1 and2-1 shifts are power-ON coastdowns (a 3-2 power-ON coastdown shift isnot made); the 4-3 is typically a power-OFF shift (it may be power-ON ifthe shift is inhibited by the below "backlash" logic).

As illustrated in FIG. 24F, a graph of speed (r.p.m.) versus time isshown at 2300 for an adaptive fourth to third (4-3) gear coastdownshift. Curve 2302 represents the output speed N_(o) or target speedN_(j) for third gear. Curve 2302 represents the engine speed N_(e).Curve 2306 represents turbine speed N_(t).

If a shift is scheduled by the transmission controller 3010 when N_(e)is less than N_(j), the start of the 4-3 shift will occur at point 2308.As the shift occurs, N_(t) will increase and cross over N_(e), asindicated by point 2310, from positive to negative torque, resulting ina "clunk" of the drivetrain.

The present invention provides the feature of delaying or inhibiting thestart of the shift by the transmission controller 3010 until N_(e) is atleast equal to or greater than N_(j), as indicated by point 2312. Thisis accomplished by delaying the actuation and/or deactuation 335 (i.e.turning ON and/or OFF) of the appropriate solenoid-actuated valves. Byinhibiting the shift, N_(t) will remain less than N_(e) during theentire shift, resulting in only positive torque and preventing any"clunk" of the drivetrain.

As illustrated in FIG. 24G, a phase plane graph of turbine acceleration(alpha_(t)) versus turbine speed N_(t) minus target N_(j) (first gear)for a second to first (2-1) gear coastdown shift is shown at 2320. Thesolid line curve 2322 represents the desired acceleration(alpha_(desired) or α*) which is a function of slip. Alpha_(desired)goes to a negative value in the hold-speed region of the downshift.

The present invention provides methodology for controlling alpha_(t) atpoint 2324 which is approximately 25 r.p.m. This is accomplished byusing proportional control (DC_(alpha) or DCα). DC_(alpha) is usedduring coastdown shifts because real tight control hold-speed is neededand is lacking otherwise.

Referring to FIG. 24G, curve 2326 represents the vent release element(VRE) which is identified during a coastdown shift by alpha_(desired)minus a predetermined value such as 1000. VRE is used where the applyingelement may be ON, or it is desired to vent the release element fasterthan normal DC_(alpha) would (rather than backing off the releaseelement's duty cycle by DC_(alpha), which would eventually release theelement). If actual alpha_(t) is below VRE curve 2326, as indicated bythe arrow, the release element is turned OFF. This would result inactual alpha_(t) coming back above the VRE curve 2326 if the applyelement was not ON. Once alpha_(t) was above the VRE curve 2326, themethodology would instruct the transmission controller 3010 to turn therelease element ON. If the apply element was ON, alpha_(t) would notcome back above the VRE curve 2326.

Referring to FIG. 24G, curve 2328 represents hold the apply pressure(HAP). HAP is used where there is too much negative alpha_(t). In otherwords, HAP is used where alpha_(t) is less than a predetermined valuesuch as -1700. HAP prevents the apply element from applying hard quicklyby duty cycling the apply element to maintain it at a predeterminedpressure. This prevents the apply element from building up torque anyfaster in the hold-speed region, causing alpha_(t) to come back abovethe HAP curve 2328.

As illustrated in FIG. 24H, a plot of actual turbine acceleration(alpha_(t)) represented by curve 2330 and desired acceleration(alpha_(desired) or α^(*)) represented by curve 2332 is shown for asecond to first (2-1) gear coastdown shift. A logic curve 2234represents VRE and logic curve 2236 represents HAP. A plot of turbinespeed N_(t) represented by curve 2338, target speed N_(j) represented bycurve 2340, and output speed N_(o) represented by curve 2342 is shownfrom the start to the end of the second to first gear coastdown shift.Logic curves 2344 and 2346 show the element logic for the releaseelement (two/four shift clutch 308) and the apply element (low/reverseclutch 310), respectively.

Referring to FIG. 24H, the release element is ON until the start ofshift at point 2348. At that time, the methodology turns the releaseelement OFF. Simultaneously, the apply element which has been previouslyOFF is maintained OFF. Also, curve 2338 of N_(t) is less than curve 2340of N_(j).

After the start of shift at point 2348, alpha_(t) starts to rise orincrease. When alpha_(t) crosses alpha_(desired) at point A (wait untilslip), the release element is turned ON or reapplied using duty cyclebang-bang (DC_(bb)). DC_(bb) is used until alpha_(t) again crossesalpha_(desired) at point B. Also, N_(t) crosses N_(j) at point B. Atpoint B, the release element switches from DC_(bb) to proportionalcontrol (DC_(alpha) or DCα).

Referring to FIG. 24H, the apply element comes on before point B to beready at the right time into hold-speed region (starts at point C). Atpoint C, alpha_(desired) enters the hold-speed region. The releaseelement against switches to DC_(bb) while the apply element is underDC_(alpha). If alpha_(t) goes too far below alpha_(desired), VRE isapplied as previously described. Alternatively, if alpha_(t) is belowthe HAP value, HAP will be applied as previously described. Thus, N_(t)is matched to N_(j) and alpha_(t) is matched to alpha_(desired) at theend of the shift by using DC_(bb), DC_(alpha), VRE and/or HAP.

Referring to FIG. 24I, the methodology for the release element usedduring a coastdown or kickdown shift is generally shown at 2400. Themethodology enters through bubble 2402 and advances to diamond 2404. Atdiamond 2404, the methodology determines whether the conditions arepresent indicating that the apply element is applying. In other words,are conditions present for VRE (i.e. THR <5° and alpha_(t)<alpha_(desired) -1000). If that criteria is true, the methodologyadvances to block 2406 and vents the release element (applies VRE). Themethodology then returns. If that criteria is not true, the methodologyadvances to block 2408 and establishes the phase of the shift: phase 1equals the start; phase 2 equals the feather start (reduction in desiredacceleration); and phase 3 equals target speed (hold-speed). This isaccomplished by performing speed calculations and setting a flag foreach phase of the shift. The methodology then advances to block 2410 andperforms a pre-DC_(alpha) flag check by setting the flag with slip andalpha_(t) is HI or the release element is below fill volume, andclearing the flag with a change in the phase of the shift. Themethodology then advances to block 2412 and performs a dutycycle_(alpha) flag check. The methodology sets the DC_(alpha) flag whenthe pre-DC_(alpha) flag has been set and alpha is LOW (i.e. alpha_(t),high-to-low crossover) and it cleared with the change in phase of theshift. The methodology then advances to diamond 2414 and determineswhether the DC_(alpha) flag has been set. If the flag has been set, themethodology advances to block 2416 and uses DC_(alpha) control orDC_(alpha) on release element. DC_(alpha) control is when the totalperiod is fixed and the ON and OFF time is calculated and adjusted (i.e.variable ON and OFF time). The methodology then returns. If the flag hasnot been set, the methodology advances to diamond 2418 and determineswhether alpha_(t) is HI. If that criteria is true, the methodologyadvances to block 2418 and performs DC_(bang-bang) control or DC_(bb) onthe release element and returns. DC_(bb) control is when the totalperiod is fixed and the ON and OFF time is fixed (e.g. at 60% ON). Ifthat criteria is not true, the methodology advances to block 2420 andvents the release element and returns.

Referring to FIG. 24J, the methodology for the apply element isgenerally shown at 2450 for a coastdown or kickdown shift. Themethodology enters through bubble 2452 and advances to diamond 2454. Atdiamond 2454, the methodology determines whether the phase of the shiftis equal to one or two and N_(t) is less than N_(j). If any of thiscriteria is true, the methodology advances to diamond 2456 anddetermines whether N_(t) is above the speed associated with the correctapply timing (i.e. will element be late). In other words, themethodology determines whether N_(t) is greater than S (kickdown startvalve previously described). If that criteria is true, the methodologyadvances to block 2458 and applies the apply element and returns. Ifthat criteria is not true, the methodology advances to block 2460 andvents the apply element and returns.

At diamond 2454, if any of that criteria is not true, the methodologyadvances to diamond 2462 and determines whether the apply element willapply within 120 ms if run at a predetermined duty cycle by looking atthe fill volume (V_(f)). If that criteria is not true, the methodologyadvances to block 2464 and applies the apply element and returns. Ifthat criteria is true, the methodology advances to diamond 2466 anddetermines whether vehicle speed or N_(o) is greater than apredetermined speed such as 8 mph and less than 300 r.p.m. of run awayfor the turbine 128. If that criteria is true, the methodology advancesto block 2468 and applies the apply element and returns. If thatcriteria is not true, the methodology advances to diamond 2468 anddetermines whether conditions are present indicating apply elementshould "hold" (for a coastdown, alpha_(t) very negative). In otherwords, the methodology determines whether the conditions are present toapply HAP (i.e. THR<5° and α_(t) <-1700). If that criteria is true, themethodology advances to block 2470 and performs DC_(HAP) on the applyelement and returns. If that criteria is not true, the methodologyadvances to block 2472 and performs DC_(alpha2) (secondary element DCacceleration control) on the apply element and returns.

Another feature of the present invention used during a coastdown shiftis a methodology called "wait-for-slip". At the beginning of thecoastdown shift, the release element is vented. Whenever slip is present(i.e. N_(t) ≠N_(j)) and V_(I) <V_(f) for the release element and V<V_(f)for the apply element, and THR≧5° or 2-1 or 3-1 shift is occurring, themethodology controls the release element at a low limit percent ON forits DC_(alpha). The methodology attempts to keep the release elementfrom further venting because the release element may be needed to applyagain. Once, the above conditions are no longer present, the releaseelement continues to vent.

ACCUMULATOR CONTROL

As illustrated in FIGS. 5A-L, the hydraulic system 600 includesaccumulators 630,640, 642, 644 for the clutch assemblies 302,304, 308and 310, respectively. The accumulators provide mechanical cushion sothat extreme changes in pressure are not realized as thesolenoid-actuated valves are turned ON or OFF. These accumulators helpreduce the axial length of the transmission 100 and give moreflexibility to the hydraulic system. This is advantageous over priorsystems which used large cushion springs built in the clutch packs,increasing the axial length of the transmission.

As illustrated in FIG. 24K, a curve 2480 of pressure versus time forapplying and venting (releasing) of an element or clutch is shown. Theaccumulator control zone, represented by part 2482 of the curve 2480,provides compliance or softness so that it takes time to develop a largechange in pressure. Otherwise, if no accumulator was used, the slope ofthis part of the curve would be steeper and a small change in ON timewould result in a large change in pressure, making torque capacity andshift quality unbearable.

In other words, control is performed in the accumulator control zone toprevent large excursions in the output torque (T_(o)) which would createjerkiness or harshness in shift quality. For example, turning therelease element ON during slip or bump-along without an accumulatorwould produce a steeper slope in the output torque, resulting in aninability to limit slip without harsh control.

TORQUE PHASE SHIFT CONTROL METHODOLOGY

The learned term for apply rate is torque phase duty cycle, DC_(t). Thepurpose of the torque phase duty cycle is to make the hand-off smoothbetween the release element letting go of torque and the apply elementtaking over torque. This is accomplished by timing the apply element tohave sufficient capacity to start the speed change just as the releaseelement capacity reaches zero. In other words, the methodology attemptsto build-up apply element torque capacity to match torque fall-offcapacity of the release element.

The torque phase duty cycle is adaptively adjusted to match torquebuild-up of the apply element to torque fall-off of the release elementaccording to the following equation: ##EQU4## Where: THR=throttle angle

B=slip (40 r.p.m.)

The above equation is based on a table value, DC_(tt) or nominal DC_(t)values (fixed % ON time) based on throttle angle, plus a learnedadjustment, DC_(ta). Since the intent is to have the speed change beginas the release element net-apply-pressure reaches zero, the methodologyselects a DC_(t) which will achieve the start of speed change at aninterval after the start of venting of the release clutch. This intervalis equal to the learned time to release at zero degrees throttle angleplus an allowance for one bump-along cycle. The transmission controller3010 does this by achieving and maintaining t_(f) equal to zero untilslip occurs, then DC_(t) is allowed to proceed.

Referring to FIG. 24D, curve 2500 represents the logic state of therelease element. Curve 2502 represents slip in the transmission 100. Atpoint 2504 on curve 2500, the release element is turned OFF or starts tovent. The interval between the start of vent at point 2504 until thestart of speed change, which is point 2506 on curve 2502, is known as t*which is a predetermined value different for each upshift. Curve 2508represents the logic state of the apply element. At point 2510 on curve2508, the apply element is initially turned OFF or vented. At point2510, t_(f) is equal to zero and DC_(t) starts for the apply element.

The slope of DC_(t) is tailored so that it matches the build-up in applyelement torque capacity. For throttle angles greater than 10°, the applyelement is given a 10% boost in its duty cycle so that the actualturbine acceleration (alpha_(t) or α_(t)) will achieve the desiredacceleration (alpha_(desired) or α*).

As illustrated in FIG. 24D, curve 2512 represents the desiredacceleration (alpha_(desired)) and curve 2514 represents the actualturbine acceleration (alpha_(t)). At point 2506 on curve 2502, the speedchange begins. Alpha_(t) is greater than alpha_(desired). Therefore,DC_(ta) adds 10% boost in ON time to DC_(t) for the apply element suchthat alpha_(t) will be momentarily equal to alpha_(desired) at or nearthe end of DC_(t).

As shown and described above, DC_(ta) is the learned adjustment toDC_(t). DC_(ta) is used so that the start of the speed change from theinitial release occurs within a predetermined time period called time tostart speed change (t_(n)). This time is when it is desired to have thespeed change begin because the release element pressure will havedecayed down to the fill pressure such that no torque capacity is on theelement. Otherwise, if the speed change begins earlier or prior to thistime, fight will occur because both the apply and release element havecapacity. t_(n) is defined as follows:

    t.sub.n =t.sub.t -t.sub.v at the end of shift,

where:

t_(t) =value of time `t` with N_(t) ≧5947 N_(i) -B or previous value oft_(t) with N_(t) <N_(i) -B

t_(v) =value of time `t` at initial venting of release element or lastoccurrence of V≧V_(f) +V_(a) for release element

Initially, DC_(ta) is equal to zero (i.e. battery disconnect). Then,DC_(ta) is defined as follows: ##EQU5## In the above equation, t^(*a) isan adjusted value of t^(*) (a predetermined table value) based on alearned value of K_(s). K_(s) is used to predict where the first cycleof bump-along occurs because of changes in temperature. K_(s) is used toadjust t^(*) based on temperature so that start of DC_(t) for the applyelement occurs just prior to the first bump-along cycle.

Referring to the equation for DC_(t), a delta term is used when thetransmission system has not learned out properly the above variables. Ift^(*) is less than the start of speed change at point 2506 on curve2502, the % ON time for DC_(t) is increased or incremented until thestart of speed change begins at the end of _(t) ^(*). Thus, the deltaterm provides added protection by reacting immediately.

GARAGE SHIFT METHODOLOGY

Referring to FIG. 24L, a shift tape representation of variouscharacteristics of the transmission 100 is shown. Curve 2502 representsthe logic state of the apply element and curve 2504 represents the logicstate of the release element. Curve 2506 represents the desiredacceleration (alpha_(desired)) and curve 2508 represents the actualturbine acceleration (alpha_(t)). Curve 2510 represents the pressure oflow/reverse element and curve 2512 represents the pressure of thereverse element.

When the manual valve 604 is shifted to reverse R, the low/reverseelement starts to vent. The low/reverse clutch solenoid-actuated valve636 is turned OFF as indicated by point 2514 on curve 2502. The pressurein the low/reverse element starts to decrease or decay as shown by part2516 of curve 2510. During this time, the reverse element is filling andthe pressure starts to increase as shown by part 2518 of curve 2512.When the pressure in the low/reverse element has decayed to a fairly lowlevel as indicated by point 2520 on curve 2510, the low/reverse elementis reapplied under DC control at point 2520 on curve 2504.

ON-BOARD DIAGNOSTICS

The on-board diagnostics provide diagnostic test routines to quicklyidentify control problems. An example of such diagnostics is found inU.S. Pat. No. 4,612,638, issued September 16, 1986, in the name ofKissel, which is hereby incorporated by reference. The transmissioncontroller 3010 also includes a set of diagnostics to isolatetransmission problems.

Referring to FIG. 25A, the methodology for the on-board diagnostics isshown. At the start of the methodology in bubble 2600, the methodologyadvances to diamond 2602 and determines whether a command (CMD) wasreceived by looking for a string of bytes from a communications port onthe transmission controller 3010. If a command was not received, themethodology advances to block 2642 to be described herein. If a commandwas received, the methodology advances to diamond 2604 and determineswhether the command received was for a PRNODDL start test. If thecommand received was for a PRNODDL start test, the methodology advancesto block 2606 and calls the PRNODDL test routine or methodology to bedescribed (See FIG. 25B). The methodology then returns to diamond 2602.

At diamond 2604, if the command received was not for a PRNODDL starttest, the methodology advances to diamond 2608 and determines whetherthe PRNODDL test passed by looking for a flag for example. If thePRNODDL test did not pass, the methodology advances to block 2642. Ifthe PRNODDL test did pass, the methodology advances to diamond 2610 anddetermines whether the command received is for a solenoid/pressureswitch test routine based on the transmission 100 operating in park Pwith the engine of the vehicle off by looking for a coded output or aflag for example. If the command was received, the methodology advancesto diamond 2612 and determines whether the engine is off (N_(e) =0). Ifthe engine is not off, the methodology advances to block 2642. If theengine is off, the methodology advances to block 2614 and calls the parkengine-off test to be described (See FIG. 25C).

At diamond 2610, if the command received was not for the park with theengine off solenoid/pressure switch test, the methodology advances todiamond 2616 and determines whether the engine is on (N_(e) is greaterthan or equal to a predetermined value such as idle speed). If thatcriteria is not true, the methodology advances to block 2642. If thatcriteria is true, the methodology advances to diamond 2618 anddetermines whether the command received was for a solenoid/pressureswitch test routine based on the transmission 100 operating in park withthe engine on (N_(e) greater than or equal to the engine idle speed). Ifthe command was received, the methodology advances to block 2620 andcalls the park engine test to be described (See FIG. 25D). Themethodology then advances to block 2642.

At diamond 2618, if the command received was not for park with theengine on solenoid/pressure switch test, the methodology advances todiamond 2622 and determines whether the command received was for asolenoid/pressure switch test routine based on the transmission 100operating in reverse with the engine on. If that criteria is true, themethodology advances to block 2624 and calls the reverse test to bedescribed (See FIG. 25E). The methodology then advances to block 2642.

At diamond 2622, if the command received was not for reverse with theengine on, solenoid/pressure switch test, the methodology advances todiamond 2626 and determines whether the command received was for asolenoid/pressure switch test routine based on the transmission 100operating in neutral with the engine on. If that criteria is true, themethodology advances to block 2628 and calls the neutral test to bedescribed (See FIG. 25F). The methodology then advances to block 2642.

At diamond 2626, if the command received was not for neutral with theengine on solenoid/pressure switch test, the methodology advances todiamond 2630 and determines whether the command received was for asolenoid/pressure switch test routine based on the transmission 100operating in overdrive with the engine on. If that criteria is true, themethodology advances to block 2632 and calls the overdrive test to bedescribed (See FIGS. 25G and 25H). The methodology then advances toblock 2642.

At diamond 2630, if the command received was not for overdrive with theengine on solenoid/pressure switch test, the methodology advances todiamond 2634 and determines whether the command received was for asolenoid/pressure switch test routine based on the transmission 100operating in low or drive with the engine on. If that criteria is true,the methodology advances to block 2636 and calls the low/drive test tobe described (See FIG. 25I). The methodology then advances to block2642.

At diamond 2634, if the command received was not for low or drive withengine on solenoid/pressure switch test, the methodology advances todiamond 2638 and determines whether the command received was for a speedsensor test made with the engine on. If that criteria is true, themethodology advances to block 2640 and calls the speed sensor test to bedescribed (See FIG. 25J). The methodology then advances to block 2642.

At diamond 2638, if the command received was not for a speed sensortest, the methodology advances to diamond 2644 and determines whetherthe command received was for a solenoid response test. If the commandreceived was for a solenoid response test, the methodology advances toblock 2646 and calls the solenoid response test to be described (SeeFIG. 25K). Once this has been completed, or the command received was notfor a solenoid response test, the methodology advances to diamond 2262.At diamond 2262, the transmission controller 3010 determines whether thecommand received was for diagnostic table data. If yes, the methodologyadvances to block 2644 and sends out diagnostic table data such asN_(e), N_(t) and N_(o) from the transmission controller 3010 to anotherelectronic device. The methodology then returns. If the command was notfor diagnostic table data, the methodology returns.

Referring to FIG. 25B, the methodology for the PRNODDL test routine ormethodology in block 2606 of FIG. 25A is shown. This methodology checksthe operation of the PRNODDL contact switch sensors (NS₁, NS₂, RL₁, RL₂)previously described. At the start of the test in bubble 2650, themethodology advances to diamond 2652 and determines whether a newcommand was received from the communications port as previouslydescribed. If a new command was not received, the methodology advancesto block 2654 and gets the information as to the position of the manuallever 578 (i.e. park P) (See FIG. 19) as previously described. Themethodology then advances to block 2656 and updates the memory of thetransmission controller 3010 and compares the previous position of themanual lever 578 to the present position to determine a match. Themethodology also sets a flag in the PRNODDL start test to indicate thepresent position of the shift lever (SLP) or manual lever 578. Themethodology then returns to diamond 2652.

At diamond 2652, if a new command was received, the methodology advancesto diamond 2660 and checks the PRNODDL status for whether the test waspassed or failed. If the test passed, the methodology advances to block2662 and sets a test passed bit or flag. If the test failed, themethodology advances to block 2664 and sets a test failed flag. Themethodology advances from blocks 2662 and 2664 to block 2666 and outputsthe flags to a diagnostic readout box (DRB) or the like. The methodologythen returns to the main loop.

Referring to FIG. 25C, the solenoid/pressure switch test for thetransmission 100 operating in park with engine off routine ormethodology in block 2614 of FIG. 25A is shown. The methodology is usedto check the operation of the solenoid-actuated valves 630, 632, 634 and636 and pressure switches 646, 648 and 650 (FIGS. 5A-L). At thebeginning of the methodology in bubble 2670, the methodology advances todiamond 2672 and determines whether the shift lever position (SLP) 606is park P as previously described. If the SLP 606 is not park, themethodology returns to the main loop. If the SLP 606 is park, themethodology advances to block 2674 and calls the pressure switch testroutine or methodology, previously described in connection with FIGS.21A and 21B, to test all pressure switches 646, 648 and 650. Themethodology then advances to diamond 2676 and determines whether anyflags were set. If no flags were set, the methodology advances to block2678 and outputs a "test-passed" code to the DRB. The methodology thenreturns to the main loop.

At diamond 2676, if any of the flags are set, the methodology advancesto diamond 2680 and determines whether the low/reverse pressure switch650 is on or pressurized by checking on input port to see if ON or OFF.If that criteria is true, the methodology advances to block 2682 andoutputs a code that the "low/reverse pressure switch not off" to theDRB. The methodology advances from block 2682 to diamond 2684. Atdiamond 2684, the methodology determines whether the two/four pressureswitch 648 is on or pressurized as previously described. If thatcriteria is true, the methodology advances to block 2686 and outputs acode that "two/four pressure switch is not off". The methodology thenadvances to diamond 2688 and determines whether the overdrive pressureswitch 646 is on or pressurized as previously described. If thatcriteria is not true, the methodology returns to the main loop. If thatcriteria is true, the methodology advances to block 2690 and outputs acode that the "overdrive pressure switch is not off". The methodologythen returns to the main loop.

Referring to FIG. 25D, the methodology for the solenoid/pressure switchtest for the transmission 100 operating in park with engine on (i.e.N_(e) greater than a predetermined value) of block 2620 of FIG. 25A isshown. At the beginning of the methodology in bubble 2700, themethodology advances to diamond 2702 and determines whether the SLP 606is park P as previously described. If the SLP 606 is not park, themethodology returns to the main loop. If the SLP 606 is park, themethodology advances to diamond 2704 and determines whether the enginetemperature is hot, from the transmission temperature routine aspreviously described, by looking for a flag for example. If the enginetemperature is not hot, the methodology returns to the main loop. If theengine temperature is hot, the methodology advances to block 2706 andcalls the pressure switch test previously described to apply thetwo/four 648 and overdrive 646 pressure switches. The methodology thenadvances to diamond 2708 and determines whether the two/four 648 oroverdrive 646 pressure switch is on or pressurized as previouslydescribed. If either pressure switch is on, the methodology advances toblock 2710 and outputs "PRNODDL failure" code to the DRB. Themethodology then returns to the main loop.

At diamond 2708, if the two/four 648 or overdrive 646 pressure switch isnot on or pressurized, the methodology advances to diamond 2712 anddetermines whether the difference between N_(e) and N_(t) is greaterthan a predetermined value such as 100 r.p.m. If that criteria is true,the methodology advances to block 2714 and stores in memory the ratio"neutral" error code. Once this has been accomplished or the differenceis not greater at diamond 2712, the methodology advances to diamond 2716and determines whether the difference between N_(t) and N_(e) is greaterthan a predetermined value such as 100 r.p.m. If that criteria is true,the methodology advances to block 2718 and stores in memory an enginespeed "N_(e) " error code. Once this has been accomplished or thedifference is not greater at diamond 2716, the methodology advances toblock 2720 and calls the pressure switch test to release the two/four648 and overdrive 646 pressure switches. The methodology then advancesto block 2722 and calls a solenoid test for the low/reversesolenoid-actuated valve 636. The solenoid test in an internal routinewhich turns the solenoid ON or OFF to check for pressure and spikeresponse. The methodology then advances to diamond 2724 and determineswhether the low/reverse pressure switch 650 was on or pressurized. Ifthe pressure switch 650 is not on, the methodology advances to block2726 and stores in memory an error code that the "low/reverse pressureswitch not on". The methodology then advances to diamond 2728. Atdiamond 2728, the transmission controller 3010 determines whether aspike detected bit or flag (i.e. flyback voltage) was set. If the spikedetected bit or flag was not set, the methodology advances to block 2730and stores in memory a "no continuity" error code. The methodology thenadvances to diamond 2732.

At diamond 2732, the transmission controller 3010 determines whether thelow/reverse pressure switch 650 is off or not pressurized. If thatcriteria is not true, the methodology advances to block 2734 and storesin memory an error code that the "low/reverse pressure switch not off".The methodology then advances to diamond 2736.

At diamond 2736, the transmission controller 3010 determines whether anyerror codes are stored. If any error codes are stored, the methodologyadvances to block 2338 and sends out the error codes to the DRB. Themethodology then returns to the main loop. If there are no error codesstored, the methodology advances to block 2740 and sends out a"test-passed" code. The methodology then returns to the main loop.

Referring to FIG. 25E, the methodology for the solenoid/pressure switchtest for the transmission 100 operating in reverse gear with the engineon of block 2624 of FIG. 25A is shown. At the start of the methodologyin bubble 2750, the methodology advances to diamond 2752 and determineswhether the SLP 606 is reverse R. If the SLP 606 is not reverse, themethodology returns to the main loop. If the SLP 606 is reverse, themethodology advances to block 2756 and calls the pressure switch testroutine previously described to apply the low/reverse 650, two/four 648and overdrive 646 pressure switches. The methodology then advances todiamond 2758 and determines whether any of the pressure switches 646,648 and 650 are on or pressurized. If any pressure switches are on, themethodology advances to block 2760 and stores in memory a "PRNODDL" failerror code. The methodology then advances to block 2762 and turns off orde-energize all solenoids of the solenoid-actuated valves 630, 632, 634and 636. The methodology then advances to diamond 2764 and determineswhether there are any error codes. If there are any error codes, themethodology advances to block 2766 and ships out the error codes. Themethodology then returns to the main loop.

At diamond 2764, if there are no error codes, the methodology advancesto block 2768 and ships out a test passed signal. The methodology thenreturns to the main loop.

Referring to FIG. 25F, the methodology for the solenoid pressure switchtest routine for the transmission 100 operating in neutral gear with theengine on of block 2628 of FIG. 25A is shown. At the start of themethodology in bubble 2770, the methodology advances to diamond 2772 anddetermines whether the SLP 606 is neutral as previously described. Ifthe SLP 606 is not neutral, the methodology returns to the main loop. Ifthe shift lever position is neutral, the methodology advances to block2774 and calls the pressure switch routine previously described to applyor turn on the two/four 648, overdrive 646 and low/reverse 650 pressureswitches. The methodology then advances to block 2776 and turns OFF thesolenoids of the solenoid-actuated valves 630, 632, 634 and 636 at theend of the main loop. The methodology then advances to diamond 2778 anddetermines whether the two/four 648 or overdrive 646 pressure switcheswere on or pressurized. If either pressure switch 646 or 648 was on, themethodology advances to block 2780 and stores in memory a "PRNODDLfailure" error code. The methodology then advances to diamond 2782.

At diamond 2782, the transmission controller 3010 determines whether thelow/reverse pressure switch 650 was on or pressurized. If the pressureswitch 650 was not on, the methodology advances to block 2784 and storesin memory an error code that the "low/reverse pressure switch not on".The methodology then advances to diamond 2786.

At diamond 2786, the transmission controller 3010 determines whetherthere are any error codes. If there are error codes, the methodologyadvances to block 2788 and ships out the error codes. The methodologythen returns to the main loop. If there are no error codes, themethodology advances to block 2790 and ships out a test passed signal.The methodology then returns to the main loop.

Referring to FIGS. 25G and 25H, the methodology for the solenoidpressure switch test routine for the transmission operating in overdrivewith the engine on of block 2632 of FIG. 25A is shown. At the start ofthe methodology in bubble 2800, the methodology advances to diamond 2802and determines whether the SLP 606 is overdrive OD as previouslydescribed. If the SLP 606 is not overdrive, the methodology returns tothe main loop. If the SLP 606 is overdrive, the methodology advances to2806 and calls the solenoid test for the two/four shiftsolenoid-actuated valve 634. The methodology then advances to diamond2808 and determines whether the two/four pressure switch 648 was on orpressurized. If the pressure switch 648 was not on, the methodologyadvances to block 2810 and stores in memory an error code that the"two/four pressure switch 648 was not on". The methodology then advancesto diamond 2812 and determines whether a spike detected bit was set aspreviously described. If the bit was not set, the methodology advancesto block 2814 and stores a "no continuity" error code for the two/fourshift solenoid-actuated valve 634. The methodology then advances todiamond 2816 and determines whether the two/four pressure switch 648 wasoff or not pressurized. If the pressure switch 648 was not off, themethodology advances to block 2818 and stores an error code that the"two/four pressure switch not off". The methodology then advances toblock 2820.

At block 2820, the methodology calls the solenoid test for the overdrivesolenoid-actuated valve 632. The methodology then advances to diamond2822 and determines whether the overdrive pressure switch 646 was on orpressurized. If the pressure switch 646 was not on, the methodologyadvances to block 2824 and stores an error code that the "overdrivepressure switch was not on". The methodology then advances to diamond2826 and determines whether the overdrive pressure switch 646 was off ornot pressurized. If the pressure switch 646 was not off, the methodologyadvances to block 2828 and stores an error code that the "overdrivepressure switch not off". The methodology then advances to diamond 2830and determines whether a spike detected bit is set. If a spike detectedbit was not set, the methodology advances to block 2832 and stores a "nocontinuity" error code for the overdrive solenoid-actuated valve 632.The methodology then advances to diamond 2834 and determines whether anyerror codes were stored. If there are error codes stored, themethodology advances to block 2836 and ships out all error codes. Themethodology then returns.

At diamond 2834, if no error codes are stored, the methodology advancesto block 2838 and stores in memory a solenoid mask (i.e. logical states)to turn ON the underdrive solenoid-actuated valve 630. The methodologythen advances to block 2840 and clears any spike detected bit. Themethodology then advances to diamond 2842 and determines whether a spikedetected bit was set. If a spike detected bit was not set, themethodology advances to block 2844 and stores a "no continuity" errorcode for the underdrive solenoid-actuated valve 630. The methodologythen advances to block 2846 and sets a solenoid mask to turn ON thetwo/four solenoid-actuated valve 634. The methodology then advances todiamond 2848 and determines whether turbine speed N_(t) is equal tozero. If N_(t) is not equal to zero, the methodology advances to block2850 and stores in memory a ratio (2nd) error code. The methodology thenadvances to block 2852 and turns OFF or releases the underdrivesolenoid-actuated valve 630. The methodology then advances to diamond2854 and determines whether N_(t) is greater than zero. If N_(t) is notgreater than zero, the methodology advances to block 2856 and releasesthe two/four shift solenoid-actuated valve 634. The methodology thenadvances to block 2858.

If N_(t) is greater than zero, the methodology advances to block 2858and sets a solenoid mask to turn ON the low/reverse solenoid-actuatedvalve 636. The methodology then advances to diamond 2860 and determineswhether the low/reverse pressure switch 650 is on or pressurized. If thepressure switch 650 is on, the methodology advances to block 2862 andstores in memory a "solenoid switch valve" (SSV) error code. Themethodology then advances to block 2864 and releases allsolenoid-actuated valves 630, 632, 634 and 636. The methodology thenadvances to diamond 2866 and determines whether there were any errorcodes. If there are any error codes, the methodology advances to block2867 and ships out the error codes. The methodology then returns to themain loop. At diamond 2866, if there were no error codes, themethodology advances to block 2868 and ships out a test passed code. Themethodology then returns to the main loop.

Referring to FIG. 25I, the methodology for the solenoid pressure switchtest routine for the transmission 100 operating in low or drive with theengine on of block 2636 of FIG. 25A is shown. At the start of themethodology in bubble 2870, the methodology advances to diamond 2871 anddetermines whether the SLP 606 is low L or drive D as previouslydescribed. If the SLP 606 is not low or drive, the methodology returnsto the main loop. If the SLP 606 is low or drive, the methodologyadvances to block 2872 and calls the pressure switch test previouslydescribed to turn ON the two/four clutch solenoid-actuated valve 634.The methodology advances to diamond 2873 and determines whether thetwo/four pressure switch 648 is on or pressurized as previouslydescribed. If the pressure switch 648 is not on, the methodologyadvances to block 2874 and stores in memory an error code that the"two/four pressure switch not on". The methodology then advances toblock 2875 turns OFF the two/four shift solenoid-actuated valve 634. Themethodology then advances to diamond 2876 and determines whether thereare any error codes. If there are error codes, the methodology advancesto block 2877 and ships out the error codes. The methodology thenreturns to the main loop.

At diamond 2876, if there are no error codes, the methodology advancesto block 2878 and ships out a test passed code. The methodology thenreturns to the main loop.

Referring to FIG. 25J, the speed sensor test mode for the engine on ofblock 2640 of FIG. 25A is shown. At the beginning of the methodology inbubble 2880, the methodology advances to diamond 2881 and determineswhether the SLP 606 is reverse R as previously described. If the SLP 606is not reverse, the methodology returns to the main loop. If the SLP 606is reverse, the methodology advances to block 2882 and verifies thein-gear ratio of output speed N_(o). The methodology then advances todiamond 2884 and determines whether the transmission 100 is in reversebased on the in-gear ratio of block 2882. If the transmission 100 is notin reverse, the methodology advances to block 2885 and sets the ratio(reverse) error code. The methodology then advances to block 2886 andgets the present value of N_(o) and N_(t) and saves these values inmemory as Past N_(o) and Past N_(t), respectively. The methodology thenadvances to diamond 2887 and determines whether N_(o) equals apredetermined value such as zero. If N_(o) is not zero, the methodologyadvances to block 2888 and sets Past N_(o), the stored value of N_(o),as N_(o). The methodology then advances to diamond 2889 and determineswhether N_(t) equals zero. If N_(t) is not zero, the methodologyadvances to block 2890 and sets Past N_(t), the stored value of N_(t),as N_(t). The methodology then advances to diamond 2891 and determineswhether both N_(t) and N_(o) are zero. If that criteria is not true, themethodology then loops back to diamond 2887.

At diamond 2891, if both N_(t) and N_(o) equal zero, the methodologyadvances to diamond 2892 and determines whether Past N_(t), thepreviously stated value of N_(t), equals a predetermined value, i.e. aminimum value of N_(t) ±20 r.p.m. If that criteria is not true, themethodology advances to block 2893 and stores a ratio (neutral) errorcode. The methodology then advances to diamond 2894 and determineswhether the Past N_(o), the previously stored value of N_(o), equals apredetermined value, i.e. minimum N_(o) ±20 r.p.m. If that criteria isnot true, the methodology advances to block 2895 and stores "N_(o) "error code. The methodology then advances to diamond 2896 and determineswhether any error codes exist. If there are error codes, the methodologyadvances to block 2897 and ships out a test passed code. The methodologythen returns to the main loop.

At diamond 2896, if there are no error codes, the methodology advancesto block 2898 and ships out the error codes. The methodology thenreturns to the main loop.

Referring to FIG. 25K, the methodology for the solenoid response testmode of block 2646 of FIG. 25A is shown. At the beginning of themethodology in bubble 2900, the methodology advances to diamond 2901 anddetermines whether the transmission fluid temperature is hot aspreviously described. If the fluid temperature is not hot, themethodology returns to the main loop. If the fluid temperature is hot,the methodology advances to diamond 2902 and determines whether the SLP606 is correct. If the SLP 606 is not correct, the methodology returnsto the main loop. If the SLP 606 is correct, the methodology advances toblock 2903 and sets all bits or flags to turn OFF the solenoid-actuatedvalves 630, 632, 634 and 636. The methodology then advances to block2904 and sets all flags to turn ON the solenoid-actuated valves 630,632, 634 and 636. The methodology then advances to diamond 2905 anddetermines whether the duty cycle (DC) counter is greater than apredetermined value such as zero. If that criteria is not true, themethodology advances to block 2906 and increments the DC counter. Themethodology then loops back to block 2904.

At diamond 2905, if the DC counter is greater than zero counts, themethodology advances to diamond 2907 and determines whether the DCcounter is equal to a predetermined value such as 5. If that criteria isnot true, the methodology advances to block 2908 and sets flags for thesolenoid-actuated valves to be turned OFF. The methodology then advancesto block 2909 and increments the DC counter. The methodology then loopsback to diamond 2907.

At diamond 2907, if the DC counter is equal to 5, the methodologyadvances to block 2910 and clears the DC counter. The methodology thenadvances to diamond 2912 and determines whether a message has beenreceived from the DRB to end the test. If a message has not beenreceived to end the test, the methodology advances to block 2904previously described. If a message has been received to end the test,the methodology returns to the main diagnostic loop.

ENGINE TORQUE MANAGEMENT METHOD

Referring to FIGS. 26A through 26D, a method is disclosed to control theengine torque and coordinate its output in response to conditionsexisting in the transmission 100. More specifically, certain conditionswhich occur in the transmission 100 will dictate that the torque outputfrom the engine must be controlled in such a way so as to minimize thepotential for interference and possible damage with any of theelectronically controlled transmission components.

To this end, the methodology begins in the FIG. 26A in block 2920 bybeginning a group of steps in the engine control module starting withthe saving in memory of a normal spark advance setting. In other words,a normal spark advance is the spark advance that the engine controller3020 will calculate on its own without regard to what is happening inthe transmission 100.

Following through to the next step in decision block 2922, a redundantcheck is performed to make sure that the engine controller 3020 hasacknowledged to the transmission controller 3010 that a control signalhas been received from the transmission controller 3010. If the enginecontroller 3020 has not yet acknowledged receipt of the signal from thetransmission controller 3010, the receipt is acknowledged in block 2924.If the transmission controller 3010 has been acknowledged as checked indecision block 2922, the routine falls through to block 2926.

As previously mentioned, blocks 2922 and 2924 are a redundant check ofthe acknowledgment of the receipt of a control signal from thetransmission controller 3010 to the engine controller 3020. The purposefor the signal from the transmission controller 3010 to the enginecontroller 3020 is to time the shift event and communicate this to theengine controller 3020 to prevent unwanted conditions from interferingwith the shift event in the transmission 100 though these signals aregenerated and/or received later in the below-described methodology. Theblocks 2922 and 2924 exist here to provide a redundant check of theacknowledgement of such a signal to provide additional diagnosticinformation regarding the mechanism to transmit the signal between thetransmission controller 3010 and the engine controller 3020. Morespecifically, this signal may be transmitted between the transmissioncontroller 3010 and engine controller 3020 by means of a hardwire or bymeans of a data bus. In the case of a data bus, since instant access tothe bus might not be possible, it is recommended that the communicationof the shift event signal be handled on a hardwire basis and theacknowledgement be handled at a later time as allowed by the data busprotocols.

The next portion of the methodology of engine torque management can bebroken into two major sections. The first section deals with the portionof the FIG. 26A beginning with decision blocks or diamonds 2926 and 2934which deal with the launch or break-away condition. The second majorsection of the engine torque management methodology is illustrated inFIG. 26A by referring to diamond 2938 and 2946 for the engine torquemanagement under conditions of a shift event at wide open throttle(WOT).

Returning now to the section of FIG. 26A dealing with the launch orbreak-away condition, the overall control strategy in this condition isto control the engine speed N_(e) directly, which results in an indirectcontrol of the differential speed between the engine and the turbine 128of the torque converter 110. This indirectly controls the torque on thetorque converter 110 which provides the input into the transmission 100.It should be noted that the torque on the torque converter 110 is theitem that must be controlled within certain ranges during a launch orbreak-away condition. In other words, it is desired to control theengine speed N_(e) such that the desirable torque, which is acceptableduring a launch or break-away condition, will stay within the prescribedboundaries.

Referring again to diamond 2926, certain conditions are checked to seeif spark control is needed during launch. More specifically, theseconditions include a throttle angle greater than a predetermined valuesuch as approximately 26 degrees and a vehicle or output speed N_(o)less than a predetermined value such as approximately six miles perhour. These conditions represent those at which peak torques will occurwhich will be the maximum conditions probably experienced. If theoperation of the engine and transmission 100 can be managed properlyduring these peak torque conditions, the durability and life of thetransmission 100 can be extended.

Returning again to diamond 2926, if the conditions of throttle angle andoutput speed N_(o) are such that spark control is needed at launch, themethodology advances to block 2928 to look up or calculate a desiredmaximum engine speed N_(e) for the current output speed N_(o). Theconcept behind the utilization of a table or a formula to get thedesired maximum engine speed N_(e) with a given output speed N_(o) isderived from the fact that transmission input (or turbine torque) isequal to the engine torque as multiplied by the torque converter 110with the amount of multiplication depending on the ratio between theengine N_(e) and turbine N_(t) speeds. Using the characteristics of thetorque converter 110, a table of engine speed N_(e) versus turbine speedN_(t) can be created so that turbine torque is a constant for the launchor break-away condition. Turbine speed N_(t) is replaced by vehicle oroutput speed N_(o) in the table or formula because the latter is alreadysensed by the engine controller 3020 and is a good approximation.

The methodology next advances to block 2930 to compute an error termwhich is equal to the difference between the actual engine speed and thedesired maximum engine speed. It is desired to control this error termand drive it to zero by adjusting the spark advance versus the error asshown in block 2932. This can be done in many ways, namely by usingintegration or proportional adjustment methods including formula orlook-up tables. The important thing is to drive the error term to zeroand adjust the spark advance to accomplish that result. Next, themethodology returns to the main program.

Returning now to diamond 2926, if the conditions are not right for aspark control to occur during launch, the methodology branches fromdiamond 2926 to diamond 2934 to check to see whether or not the launchspark control methodology is finishing. If so, the methodology advancesto block 2936 to return the spark advance to its normal condition asdetermined by the engine controller 3020 and originally sensed throughblock 2920. In this particular embodiment, the spark advance is merelyramped up to the normal values. It should be appreciated that this canbe accomplished in many ways. Next, the methodology returns to the mainengine control routine.

If launch spark control is not just finishing at diamond 2934, themethodology advances to diamond 2938 to determine whether the conditionsare right for a shift spark control at wide open throttle (WOT). Morespecifically, wide open throttle is defined as when the throttle angleis greater than or equal to a predetermined value such as 53 degrees,for example. If the conditions are right for a wide open throttle shiftspark control, the methodology advances to diamond 2940 and determineswhether a start shift signal has been received. More specifically, theengine controller 3020 is signalled by the transmission controller 3010via a hardwire, for example, between the two. Upon reception of this"start-of-shift" signal, the methodology advances to block 2942 andacknowledges receipt of the signal over the CCD bus. The methodologythen advances to block 2944 and the spark advance is held to apredetermined minimum level until an "end-of-shift" signal is received.The ramp down and up and the minimum spark advance level arecollectively calibrated for both shifts to achieve a predetermined valuesuch as a 20% reduction in shift energy. Shift energy is determinedexperimentally. Oncoming element or clutch pressure is measured and thenmultiplied by delta turbine speed, the difference between old and newgear turbine speeds, to get clutch shift power. Shift power is thenintegrated over the time of the shift to get clutch shift energy. Oncethe spark advances has been ramped down to the minimum level or, if itis already there, held to that value, the methodology returns to themain engine control program.

Returning to diamond 2940, if the start-of-shift signal has not beenreceived for a wide open throttle shift, the methodology advances todiamond 2946 and determines whether an end-of-shift signal has beenreceived. If the end-of-shift signal has been received, the methodologyadvances to block 2948 and acknowledges receipt of the end-of-shiftsignal over the CCD bus. The methodology then advances to block 2950 andramps the spark advance up to its normal level. The methodology thenreturns to the main engine control program.

Returning to diamond 2938, if the conditions are not right for shiftspark control for a wide open throttle shift, the methodology advancesto block 2952 and uses a predetermined normal spark advance value. Themethodology then returns to the main engine control program. Similarly,at decision block 2946, if an end-of-shift signal has not been received,the methodology advances to block 2952 to use a normal spark advancevalue. The methodology then returns to the main engine control program.

The above-described engine torque management routine, with respect to ashift condition at wide open throttle, it done from an open loopperspective. That is, predetermined conditions are stored and utilizedin the methodology which end up approximating the control desired.However, physical differences between the transmission and engines andeven engine controllers which occur during the manufacturing process dueto tolerances of components and variations in the componentry due totemperature and other physical conditions, can cause uniquecharacteristics for the individual transmissions, engines, and/orcontrollers. Therefore, each system will have its own "signature". Morespecifically, there is no feedback provided in the above routine toadapt or confirm that the control was exactly as theoretically desired.

Therefore, additional methods are proposed which can be implementedessentially anywhere in the engine torque management shift controls forwide open throttle conditions as described above. Two control methods,in particular, are of note. The first can be performed in thetransmission controller 3010 and the second can be performed in theengine controller 3020. Both methods rely on the feedback of informationavailable in the individual controllers to closely approximate the shiftenergy that the particular clutches in the transmission 100 must absorb,by calculating the shift power from the available pieces of information.Next, the shift power is integrated to approximate the shift energywhich must be absorbed. It should be appreciated that the methodsproposed are calculations and that, without the addition of a pressuresensor to sense the actual pressure on the specific clutch at issue, adirect measurement and subsequent calculation of the actual shift powerwill be impossible.

Referring to FIGS. 26B and 26C, the two routines are displayed. Thefirst routine which shall be described is from the perspective ofclosing the loop for wide open throttle shift energy management and thesecond routine from the perspective of the engine controller 3020.

Referring to FIG. 26B, the routine can, as above-described, be placedessentially anywhere in the transmission module to work with the enginetorque management controls for shifting at wide open throttle describedin FIG. 26A. The routine or methodology is begun in block 2954 and acalculation is performed to approximate shift power. This is done byutilizing the various parameters available in the transmissioncontroller 3010, namely, turbine speed N_(t), the duty cycle (DC) of theclutches, and the conditions of the pressure switches 646, 648 and 650which will only be energized or de-energized at certain pressure levels.The calculation is performed essentially by multiplying theapproximation of the pressure on the specific clutch in question whichis derived from the duty cycle information and the pressure switches,multiplied by the turbine speed N_(t).

Next, the routine falls through to block 2956 to calculate the shiftenergy by integrating the above-calculated shift power over time. Thiscalculation represents the approximate shift energy which must beabsorbed by the particular clutch during the shift. The routine thenfalls through to block 2958 to calculate the shift energy error which isequal to a desired shift energy minus the actual shift energy calculatedabove. The desired shift energy is a predetermined amount which is amaximum condition beyond which the clutch should not be forced tooperate. The routine falls through to block 2960 to transmit the errorsignal calculated in block 2958 to the engine controller 3020.

Next, in block 2962, the engine controller 3020 must take over from thetransmission controller 3010 in block 2962 to adjust the spark advancefor the particular shift versus the error term. This utilizes the rampspark advance to a minimum level from block 2944 in FIG. 26A. Theadjustment described in block 2962 is used in the next shift which isthe result of an accumulated adaptation from previous shifts.

Referring now to the second routine to manage engine torque, the routineis also displayed in FIG. 26C and is from the perspective of the controldone in the engine controller 3020. Referring to block 2964, acalculation of the engine horsepower (hp) is made during the shiftcondition. This is done by the engine controller 3020 taking advantageof various parameters available to it, namely, parameters such as airflow, engine speed N_(e), injector pulse width (an indirect measure ofthe amount of fuel used), spark advance, etc. From these variables, theengine horsepower is approximated.

Next, in block 2966, the methodology correlates the calculated enginehorsepower with tables stored in memory to approximate the amount ofshift power which would be transmitted to the clutches in theelectronically controlled transmission 100. This table is experimentallyderived and can also be accomplished by means of using a formula. Inblock 2968, the methodology calculates the shift energy that theclutches in the transmission 100 must absorb. This, as previouslystated, is an approximation. In block 2970, the methodology calculatesthe shift energy error which is the difference between a desired shiftenergy and that calculated as actual shift energy in block 2968. Thedesired shift energy is a maximum amount that is predetermined andstored in memory.

Next, in block 2972, the engine controller 3020 adjusts the shift sparkversus the error term for use on the next shift. The above "closed loop"methods to manage the engine torque during wide open throttle shifts areboth performed from an "after the fact" perspective. In other words,they are computed after the shift has occurred and utilized for the nextoccurrence of the condition.

A technique to handle the "closing the loop" engine torque managementduring wide open throttle shifts by the engine controller 3020 is alsoillustrated in FIG. 26D. This routine essentially replaces blocks 2942and 2944 of FIG. 26A.

The methodology begins in block 2974 with the calculation of the currentengine horsepower versus time or r.p.m. This again is an approximationof the engine horsepower above-described with respect to block 2964.

Next, the methodology falls through to block 2976 to correlate thecalculated current engine horsepower to a stored table or formula ofcurrent electronically transmission shift power. This is analogous towhat occurs in block 2966 which has been described above. Themethodology then falls through to block 2978 to compare the currentshift power found during the correlation in block 2976 with anotherstored expression, namely, the nominal desired power trace representinga nominal shift power curve. This is used in block 2980 to calculate apower error which is equal to the difference between the nominal desiredpower trace and the actual shift power correlated from block 2976.

Next, the methodology advances to block 2982 to look up or calculate aspark advance to be used for this particular shift based on thecalculated power error from block 2980. The methodology then advances toblock 2984 to calculate the shift energy which will be used for furtheradjustments when next the routine is used. This is similar to theadjustments described with respect to blocks 2962 and 2972.

Referring to FIG. 26E, a shift tape for wide open throttle (WOT) launchwithout stall torque management is shown. When the operator depressesthe accelerator pedal for WOT, the throttle angle represented by curve2986 flares up immediately and levels off at WOT. This causes enginespeed N_(e), represented by curve 2987, and spark advance, representedby curve 2988, to also increase and level off at a predetermined value.Correspondingly, wheel torque, represented by curve 2989, flares to apeak before it declines due to a drop off in torque multiplication inthe torque converter 110. Wheel torque is a qualitative measure ofengine torque.

Referring to FIG. 26F, a shift tape for wide open throttle (WOT) launchwith stall torque management according to the present invention isshown. The throttle angle curve 2986, rises from rest to WOT aspreviously described. The N_(e) curve 2987 also increases until itreaches a theoretical N_(e) versus N_(o) limit which is used to maintaina theoretical amount of torque on the turbine 128. The spark advancecurve 2988 is continuously adjusted to control N_(e) along a desiredN_(e) line (N_(e) vs. N_(o) limit). This is accomplished by measuring anerror of N_(e) versus the desired N_(e) line and computing the error.The spark advance is their adjusted in proportion to the error by apredetermined method such as by point slope interpolation. As a result,N_(e) is managed, effectively managing engine torque. This can bequalitatively seen in the wheel torque curve 2989, which representsengine torque, by the elimination of a peak, leaving a rough butrelatively flat wheel torque curve.

Referring to FIG. 26G, a shift tape for a first to second (1-2) gearupshift without engine torque management is shown. Throttle angle isrepresented by curve 2990. Throttle angle is at WOT by the time to makethe shift occur. A shift timing signal represented by curve 2991 denotesthe beginning of the shift at point 2992 and the end of the shift atpoint 2993. Throttle angle is at WOT before the beginning of the shift.

At the beginning of the shift, N_(e), represented by curve 2944, andN_(t), represented by curve 2995, rise to a peak and fall to apredetermined value by the end of the shift. The fluid pressure in theapply element (two/four shift clutch 308), represented by curve 2996,starts to increase at the beginning of the shift and levels off to afairly constant value from approximately half way during the shift tothe end of the shift. Shift energy is calculated as the differencebetween N_(t) minus N_(j) multiplied by the net pressure in the oncomingclutch (which is actual pressure minus fill pressure). Similarly, wheeltorque, represented by curve 2998 levels off to a fairly constant valuefrom approximately half way during the shift to the end of the shift.Spark advance is represented by curve 2997 and is fairly constant at thebeginning of the shift and fails to its normal value by the end of theshift.

Referring to FIG. 26H, the spark advance 2997 is ramped down to thepredetermined value at the start of shift at point 2992. The sparkadvance 2997 is held at the predetermined value until the end of shiftat point 2993 where it is ramped up to predetermined normal value. As aresult, the fluid pressure 2996 in the apply element (two/four shiftclutch 308) does reach the same level as above, but also has adepression or valley 2999 in it until the end of shift. Correspondingly,N_(t) 2995 falls off more rapidly as the transmission 100 changes gears,i.e. first to second gear. This results from a drop in N_(e) curve 2994,making for rougher control but less shift energy which is calculated asdescribed above. Thus, a drop in fluid pressure of the oncoming or applyclutch and N_(t) indicate a lower shift energy.

ELECTRONICALLY CONTROLLED, ADAPTIVE AUTOMATIC TRANSMISSION SYSTEM

Referring to FIG. 27A, a block diagram of an adaptive control system3000 according to the present invention is shown. The adaptive controlsystem 3000 includes a transmission controller 3010 which is capable ofboth receiving signals from an engine controller 3020 and transmittingsignals to this engine controller 3020. While the transmissioncontroller 3010 may be readily adapted to operate without an electronicengine controller, the transmission controller 3010 according to thepresent embodiment takes advantage of the fact that most automobilestoday include a digital or computer based engine controller whichreceives and processes signals from numerous sensors. For example, FIG.27A shows that both the transmission controller 3010 and the enginecontroller 3020 receive an input signal indicative of the temperature ofthe engine (e.g., the coolant temperature). Other exemplary inputsignals shared by these controllers include one or more signals from theignition switch, a battery voltage level signal, and a signal from thedistributor or other firing angle control mechanism. With respect to theengine controller 3020, this controller will process such signals andtransmit appropriate control or command signals to various components ofthe engine. Typical computer based engine controllers will also generateand transmit advisory signals to a diagnostic alert panel in thepassenger compartment to provide a visual and/or auditory indication ofparticular engine conditions.

As indicated by the reciprocal signal lines, it should be appreciatedthat the transmission controller 3010 includes the capability ofcommunicating with existing engine controllers. For example, it may beadvisable for the transmission controller 3010 to send signals to theengine controller 3020, such as a signal indicating that thetransmission 100 is about to shift gears. As will be appreciated fromthe description below, the transmission controller 3010 is preferablyprovided with a serial communications interface to permit serial datatransfers to be made between the transmission controller 3010 and theengine controller 3020. Additionally, the transmission controller 3010may also provide diagnostic alert capabilities, such as transmittingsuitable advisory signals to the vehicle operator (e.g., "checktransmission").

Another example of some signals which may be shared by the transmissioncontroller 3010 and the engine controller 3020 are those provided by athrottle sensor 3030 and a brake switch sensor 3040. The throttle sensor3030 may be any suitable sensor which will give an indication of thepower demand placed upon the engine by the vehicle operator, such as atransducer which will indicate the present position of the throttle.Similarly, the brake switch 3040 may be any suitable sensor which willgive an indication of the application of the vehicle brake by theoperator, such as a contact switch actuated by the movement of the brakepedal in the vehicle. As will be appreciated from the description below,the transmission controller 3010 includes suitable interface circuitsfor receiving signals from the throttle sensor 3030 and the brake switch3040. Further examples of information shared between the controllers aresignals concerning vehicle type, engine type, manifold absolute pressure(MAP) and load.

One of the primary functions of the transmission controller 3010 is togenerate command or control signals for transmission 100 to thesolenoid-actuated valves 630, 632, 634, 636 contained in the hydraulicsystem 600 (FIGS. 5A-L, 8-9) of the transmission 100. In FIG. 27A, thesesolenoid-actuated valves are lumped into a solenoid block 3050 which iscontained within a dashed block labeled "Transmission". ThisTransmission block represents a suitable transmission structure whichwill operate in conjunction with the transmission controller 3010, suchas the transmission 100 described above. Thus, in the transmission 100,the solenoid block 3050 would comprise the solenoid-actuated valves 630,632, 634 and 636. Similarly, the hydraulic controls block 3060 wouldcomprise other valves contained in the hydraulic system 600, such as thepressure regulator valve 608, the manual valve 604, the T/C controlvalve 612 and so forth, as described above. Likewise, the frictionelements gear box block 3070 would comprise the multi-clutch assembly300 and the gear assembly 500 as described above. However, it should beappreciated that the adaptive control system 3000 according to thepresent invention may be used in conjunction with other suitabletransmission structures in the appropriate application.

FIG. 27A also illustrates that the Transmission block includes a PRNODDLsensor block 3080 which is responsive to a gear shift lever that isunder operator control. The PRNODDL sensor block 3080 may be comprisedof one or more suitable sensors which are capable of providing anindication to the transmission controller 3010 of the transmissionoperating mode selected through the manual actuation of the gear shiftlever. In this regard, FIG. 4B shows two contact switch sensors NS₁ andNS₂ which are mounted to the transmission case 102. The sensors NS₁ andNS₂ are mounted in proximity to the manual lever 578 in order to permita spring loaded pin of these sensors to engage and follow the peripheraltrack of a cap member 578a of the manual lever 578.

NEUTRAL START SWITCH TO SENSE SHIFT LEVER POSITION

Referring briefly now to FIG. 19, a diagrammatic representation of theoperation of the sensors NS₁ /RL₁ and NS₂ /RL₂ is shown. Specifically,FIG. 19 shows that the sensors NS₁ /RL₁ and NS₂ /RL₂ are each providedwith a spring loaded contact pin, such as pin 3082, which engages thecap member 578a of the manual lever 578. The cap member 578a is formedto permit metal areas of the manual lever 578 to extend through the capmember 578a, such as metal areas 3084. These metal areas 3084 are usedto provide an electrical ground for the sensor. Thus, as shown in thecorresponding table for the figure, each of the sensors NS₁ /RL₁ and NS₂/RL₂ will produce a digital low or ".0." signal when their sensor orcontact pin is in physical contact with one of the metal areas (e.g.,metal area 3084). For example, in the park "P" position, both of the"NS" contacts of sensors NS₁ /RL₁ and NS₂ /RL₂ will be grounded, asshown by the corresponding columns of the table under section heading"PRNODDL METHOD".

The cap member 578a also includes non-grounded areas which are formedwith trapezoidal shaped grooves, such as groove 3086. These grooves areused in connection with a set of internal contacts within the sensorsNS₁ /RL₁ and NS₂ /RL₂ to create the four-bit digital code shown in thetable for FIG. 19. These internal contacts 3088 are also illustrated inFIG. 19, which provides a schematic representation of one of the NS/RLsensors. When the contact pin 3082 of either of the sensors NS₁ /RL₁,NS₂ /RL₂ extends into one of the grooves 3086 of cap member 578a, thenthe internal "RL" contacts 3088 of that sensor will close and cause thesensor to produce a digital high or "1" signal from the electricalterminals of these contacts. As discussed previously, the internalcontacts 3088 provide a set of reverse light "RL" contacts which areused in connection with the reverse of back-up lights of the vehicle.

In operation, actuation of the gear shift lever will cause a rotation ofthe manual lever 578 to the position selected by the vehicle operator.As the manual lever 578 rotates, the sensors NS₁ /RL₁ and NS₂ /RL₂ willproduce a four-bit code which will correspond to the rotational positionof the manual lever 578. The transmission controller 3010 will thendetermine the mode of operation selected through the four-bit codeproduced by the sensors NS₁ /RL₁ and NS₂ /RL₂.

Referring again to FIG. 27A, the transmission controller 3010 receivesinput signals from the PRNODDL sensor block 3080, as well as producesoutput signals to a PRNODDL indicator contained in the passengercompartment. This PRNODDL indicator may, for example, be a suitablelight source or other appropriate indicator for providing the operatorwith a visual indication of the operating mode which has been selected.

FIG. 27A also indicates that a pressure switch block 3090 is connectedto the hydraulic controls block 3060. In connection with transmission100, the pressure switch block 3090 would comprise the pressure switches646, 648 and 650 (FIGS. 5A-L and 10). As described above, each of thesepressure switches is adapted to provide a signal indicative of apredetermined pressure level in the corresponding passageways leading toselected friction elements. Specifically, each of these pressureswitches provide a digital input signal to the transmission controller3010 which will indicate whether or not this pressure level has beenreached.

FIG. 27A also indicates that the Transmission block includes a speedsensors block 3100 which is connected to the friction elements gear box3070. In connection with the transmission 100, the speed sensors block3100 comprises the input or turbine speed sensor 320 and the outputspeed sensor 546 which are both mounted to the transmission case 102.However, as previously indicated, other suitable speed sensor means maybe provided either within or outside of the transmission case 102 inorder to provide the desired input or turbine and output speed signalsto the transmission controller 3010. The speed sensors block 3100 mayalso include a suitable engine speed sensor (e.g., hall effect device).However, if the engine controller 3020 is already receiving such a speedsignal, then this signal could be shared with the transmissioncontroller 3010 to avoid unnecessary duplication.

ELECTRONIC CONTROLLER FOR AN AUTOMATIC TRANSMISSION

Referring to FIG. 27B, a block diagram of the transmission controller3010 is shown. The first block is the serial communication interface3200 which has as its function to provide a serial communications linkwith the engine controller 3020. This serial communication interface3200 could also be used to provide a serial communication link withother appropriate microcomputer-based controllers in the vehicle. Itshould also be understood that a parallel communication could also beused in the appropriate applications.

In the present embodiment, the serial communications interface 3200utilizes the multiplexing protocol and interface technology of theChrysler Collision Detection ("C² D") Serial Data Bus. This technologyis described in the co-assigned U.S. Pat. No. 4,706,082, entitled"Serial Data Bus For Intermodule Data Communications," which issued onNovember 10, 1987; and U.S. Pat. No. 4,719,458, entitled "Method Of DataArbitration And Collision Detection In A Data Bus," which issued onJanuary 12, 1988; and U.S. Pat. No. 4,739,323, entitled "Serial Data BusFor Serial Communication Interface (SCI), Serial Peripheral Interface(SPI) and Buffered SPI Modes of Operation," which issued on April 19,1988; and U.S. Pat. No. 4,739,324, entitled "Method for SerialPeripheral Interface (SPI) in a Serial Data Bus," which issued on April19, 1988; and U.S. Pat. No. 4,742,349, entitled "Method for BufferedSerial Peripheral Interface (SPI) in a Serial Data Bus," which willissue on May 3, 1988; and in SAE paper No. 860389, entitled "ChryslerCollision Detection (C.sup. 2 D)--A Revolutionary Vehicle Network," byFrederick O. R. Miesterfield, 1986. These patents and documents are allhereby incorporated by reference.

Another function for the serial communications interface 3200 is toprovide a diagnostic interface with the transmission controller 3010 sothat service information can be provided to a technician as atroubleshooting or maintenance aid. Still another function of the serialcommunications interface 3200 is to provide a convenient data or programaccess route for in-plant testing of the transmission controller 3010during the manufacturing process.

The transmission controller 3010 also includes several other interfacecircuits which are used to receive and condition input signals from thevarious sensors identified above. For example, the transmissioncontroller 3010 includes a block 3210 which contains the interfacecircuits used to receive signals from the speed sensors 3100 and thethrottle sensor 3030. The transmission input speed signal represents theturbine speed N_(t) of the torque converter 110, while the output speedsignal represents the output speed N_(o) of the vehicle. As describedabove, both of these signals are generated by variable reluctancepick-ups (e.g., speed sensors 320 and 526). The engine speed is alsosensed by a suitable sensor, such as a hall effect pick-up in thedistributor of the engine. This technology is described in co-assignedU.S. Pat. No. 4,602,603, entitled "Ignition Distributor-Hall EffectSensor Switching System and Method," which issued on July 29, 1986 whichis hereby incorporated by reference.

The function of block 3210 is to provide input signal conditioning,filtering and conversion of the speed sensor signals to digital logiclevels. In this regard, block 3210 also includes an interface circuitfor the throttle position sensor 3030. Once this signal is properlyconditioned, this information may be shared with the engine controller3020. The throttle position sensor 3030 will give an indication as towhich angular position the throttle blade (means) is in within thethrottle body. As with other appropriate input signals, the throttleposition sensor signal is conditioned and fed through a unity gaindifferential amplifier to provide isolation, as will be described below.

The transmission controller 3010 also includes blocks 3220 and 3230which represents the interface circuits used to receive various inputsignals related to the engine ignition and PRNODDL condition.Specifically, the ignition related signals include a signal J2, and asignal S2. The signals related to the PRNODDL condition include the"neutral start" signal NS₁, and "auxiliary neutral start" signal NS₂, a"first reverse light" signal RL₁ and a "second reverse light" signalRL₂. In accordance with the preferred embodiment, the controlmethodology is responsive to the condition that these ignition switchvoltage signals are in. The reason for this is that it is appropriate tohold the transmission controller 3010 in certain predeterminedconditions depending on the position of the ignition switch and/or theneutral contact switch sensor NS₁ and/or the auxiliary contact switchsensor NS₂.

For example, the signal J2 represents the ignition voltage during therun and crank positions, and this signal will generally be either at azero voltage level or at the battery voltage level. The signal S2represents the voltage in the crank position only and is used to providethe necessary voltage for the starter relay coil of the engine. Todetermine when the transmission 100 is in a crank condition the NS₁ orneutral start switch signal is sensed along with the S2 signal to holdthe transmission controller 3010 in a reset condition during crankingdue to the possibility that the battery voltage may drop below levelrequired for proper controller operation.

Referring specifically to block 3230, the PRNODDL condition switchesprovide input signals from the contact switch sensor NS₁, the auxiliarycontact switch sensor NS₂, the first reverse light RL₁ and the secondreverse light RL₂. The PRNODDL switch block 3230 controls the switchingof the reverse lights which are connected in series. When the signalsRL₁ and RL₂ indicate a reverse condition, electrical current from theignition switch J2 is fed through a relay coil which interconnects thereverse lights to battery voltage via the relay contacts thus turning onthe backup lights on the vehicle. The PRNODDL switch block also acts incombination with the two contact switch sensors NS₁ and NS₂ to determinethe shift lever position, as discussed above.

As shown in FIG. 27B, the transmission controller 3010 includes apressure switch block 3240 which represents the interface circuit usedfor receiving and conditioning the pressure level signals from thepressure switches 3090. Each of the pressure switches provide a digitallevel signal which is either at a zero or battery voltage leveldepending upon whether or not a predetermined pressure level has beenreached. The pressure switches are used in conjunction with thelow/reverse, overdrive and two/four shift (kickdown) clutch assemblies,and generally comprise grounding switches located in the manifoldassembly 700. The pressure switch interface circuit 3240 provides inputsignal conditioning, i.e. filtering and buffering for these signals. Forexample, pull up resistors located in the manifold assembly 700 (SeeFIG. 8) to provide battery voltage when pressure switch is open arecontained in block 3090. The state of each of the pressure switchsignals is transmitted to the transmission controller 3010 to providefeedback information for use in both monitoring clutch operation and asan input to the learning logic and methodology described herein.

The heart of the transmission controller 3010 is contained in the microcore block 3250. The micro core 3250 includes an eight-bit microcomputerunit (MCU), a memory chip for storing the application or operatingprogram used by the MCU, and an interface chip for addressing androuting signals on the various lines used in the micro core busstructure. Thus, for example, several of the signals received from thecontroller's interface circuits are connected to the interface chip,which will then place these signals on the data bus when the chip isproperly addressed by the MCU.

The transmission controller 3010 also includes a watchdog/reset block3260 which provides several circuit functions in conjunction with themicro core 3250. For example, the watchdog/reset circuits 3260 willcontrol the initial start up of the MCU, watch to see if the MCU isproperly functioning, cause a reset of the MCU in response to certainregulator voltage conditions, and provide a frequency divider for thespeed signals. The watchdog/reset circuits 3260 also provide an outputto a relay driver block 3270 which is used to disconnect or turn offelectrical power to the solenoid-actuated valves 630, 632, 634 and 636in the solenoid block 3050 shown in FIG. 27A under predeterminedconditions.

One of the principal functions of the micro core 3250 is to generatecommand or control signals for transmission 100 to the solenoid driverblock 3280. The solenoid driver block includes a separate driver circuitfor the solenoid-actuated valves 630, 632, 634 and 636 contained in thesolenoid block 3050 shown in FIG. 27A. These driver circuits generatethe electrical current necessary to operate the solenoid-actuated valves630, 632, 634 and 636 in response to the control signals generated bythe MCU. The solenoid driver block 3280 also includes spike monitorcircuits which verify the operation of the solenoid driver circuits bydetecting the presence of an inductive spike (FIG. 22E) which occurswhen the solenoid coil is de-energized.

The transmission controller 3010 also includes a regulator block 3290and a test mode block 3300. The regulator block 3290 is used to advisethe watchdog/reset circuit 3260 of predetermined conditions relating tothe operation of the regulator, such as a low battery voltage condition,a high battery voltage condition, an overload condition, or an overtemperature condition in the regulator. It is a dual regulator andincludes a 5 V, switched output. The test mode block 3300 is used topermit a test mode program to be downloaded into the RAM memory of theMCU for testing the transmission system.

Referring generally to FIGS. 28A-28I, a schematic diagram of thetransmission controller 3010 is shown. Each of the FIGS. 28A-28Igenerally correspond to one of the circuit blocks shown in FIG. 27B.Thus, for example, FIG. 28A illustrates the serial communicationinterface 3200 which provides a serial communication link between thetransmission controller 3010 and the engine controller 3020. Similarly,FIG. 28B illustrates the MCU chip Z138 and the interface chip Z135 whichform part of the micro core 3250. The remainder of the micro core 3250is shown in FIG. 28C which illustrates the EPROM chip Z141 and itsassociated circuitry. It should also be noted that FIG. 28C illustratesa watchdog/reset chip Z127 and associated circuitry, which togethercorrespond to the watchdog/reset circuit 3260. A discussion of thecircuits contained in the watchdog/reset chip Z127 will be presented inconnection with FIG. 30. Similarly, a discussion of the circuitscontained in the interface chip Z135 will be presented in connectionwith FIG. 29.

Continuing with an overview of the schematic diagram for thetransmission controller 3010, FIG. 28D illustrates the speed andthrottle input interface circuits 3210. FIG. 28E illustrates the PRNODDLinterface circuits 3230 and part of the ignition switch interfacecircuits 3230. FIG. 28F illustrates the regulator circuit 3290 and therelay driver circuits 3270. FIG. 28G illustrates the solenoid drivercircuits 2880. FIG. 28H illustrates the pressure switch interfacecircuits 3240. FIG. 28I illustrates an additional serial communicationcircuit 3400 and a diagnostic communication circuit 3500.

Referring specifically to FIG. 28A, a schematic diagram of the serialcommunications interface 3200 is shown. This communications interfaceactually provides for two serial communication channels for thetransmission controller 3010. The first serial communication channel3201 is based upon the Chrysler Collision Detection (C² D) technologyidentified above. This technology is embodied in the communications chipZ14 which provides the intelligence to know when it has sent a messageout onto a serial data bus and whether or not it has won access to thebus. This bus comprises the two conductors labeled "(C² D)+" and "(C²D)". It should be noted from the above that this serial communicationsbus comprises a double ended or differential signal transmission linkwith the engine controller 3020 (or any other appropriate controller inthe vehicle which is connected to the bus structure). The communicationschip Z14 receives signals transmitted from the microcomputer chip Z138(shown in FIG. 28B) via its connection to the "PD3" port of themicrocomputer. Similarly, signals are transmitted from thecommunications chip Z14 to the microcomputer chip Z138 via the "PD2"port.

It should be noted that the communications chip Z14 is provided with aclock signal "E**" which is derived from the MCU chip's Z138 systemclock, namely the "E" Clock. As shown in FIG. 28C, two NAND gates Z195are connected in series to double buffer and double invert the E clocksignal. Signal transmissions from the MCU chip Z138 are initiated by theMCU chip Z138 which pulls down a "Control" line of communications chipZ14 via a command signal transmitted from the "PD5" port. However, thecommunications chip Z14 will actually control the transfer of data fromthe MCU chip Z138 by providing a "SCLK" clock signal to the MCU's "PD4"port, which will clock the data in and out of the MCU chip.

It should also be noted that the communications chip Z14 is turned offwhen the transmission controller 3010 is in a stop mode, such as afterthe ignition key is turned off. The communications chip Z14 is turnedoff through the "SW/5 V" power supply. The SW/5 V voltage level isderived from a dual regulator Z215 contained in the regulator circuit3290 shown in FIG. 28F. Specifically, the SW/5 V supply is switched onor enabled by the MCU Z138 in response to the ignition switch.

FIG. 28A also illustrates the second serial communications channel whichis generally designated by the reference numeral 3202. The serialcommunications channel 3202 is generally comprised of a transmit linelabeled "SCI-XMT" and a receive line labeled "SCI-REC". Each of thesetransmit and receive lines include an RC filter and a buffering inverterZ15. The transmit line SCI-XMT is connected to the "PD1" port of themicrocomputer chip Z138, while the receive line SCI-REC is connected tothe "PD.0." port of the microcomputer chip. This second serialcommunications channel may be used for example to download appropriatetest programs into the microcomputer chip Z138, such as for end of linetesting at the manufacturing facility. In one form of the presentinvention, the SCI-REC receive line is used in conjunction with the testmode to transmit a signal to the microcomputer chip Z138 which willcause a ROM resident boot load program inside the microcomputer chip tocontrol the receipt and initial execution of the test programs.

Referring to FIGS. 28B-28C, a schematic diagram of the micro core 3250is shown. The micro core 3250 for the transmission controller 3010generally comprises the microcomputer 3251 (chip Z138), the interface3252 (chip Z135), and the memory 3253 (chip Z141). In the presentembodiment, the microcomputer chip Z138 is a Motorola eight-bitmicrocomputer chip (Part No. 68HC11), which includes 256 bytes of RAMmemory and 512 bytes of EPROM (erasable electrically programmable readonly memory). However, it should be appreciated that other suitablemicrocomputer chips or microcomputer circuits could be employed in theappropriate application. Similarly, the memory 3253 (chip Z141) may beany suitable memory chip or circuit having sufficient capability tostore the computer programs which operate in accordance with the controlmethodology discussed in detail above, such as an Intel 87C257 memorychip.

As will be appreciated from FIG. 29, the interface 3252 (chip Z135) maybe any suitable chip or set of chips/circuits which generally providethe circuits illustrated in this Figure. As will be discussed below, theinterface 3252 (chip Z135) includes several internal registers forfacilitating rapid communications between microcomputer 3251 (chip Z138)and several of the other circuits contained in the transmissioncontroller 3010, such as the pressure switch interface circuit 3240. Inthe present embodiment, the various circuits illustrated in FIG. 29 havebeen combined into a single chip configuration, namely interface (chipZ135), to conserve space on the circuit board for the transmissioncontroller 3010.

Each of the pins or ports of the various chips used in the micro core3250 have been appropriately labeled, so that the various circuitconnections between these chips and the other circuits contained in theFIGS. 28A-28I. For example, the "Control" and "Idle" lines of thecommunication chip Z14 in FIG. 28A are also shown to be labeled "PA7"and "PD1" respectively. As will be appreciated from FIG. 28B, both ofthese signal lines are connected to the interface (chip Z135), as thischip contains both the "PA7" and "PB1" labeled ports.

The microcomputer 3251 (chip Z138) and the interface 3252 (chip Z135)communicate with each other via an address/data bus labeled "AD.0.-AD7".The address/data lines in this bus are bidirectional to allow thetransfer of both address and data information between the microcomputer3251 (chip Z138) and the interface 3252 (chip Z135). As illustrated inFIG. 28C, the memory (chip Z141) is also connected to this address/databus. The memory (chip Z141) is also connected to the microcomputer 3251(chip Z138) via an address bus which is comprised of address lines"A8-A15". Three of these address lines, namely address lines A13-A15,are also connected to the interface 3252 (chip Z135) for selectingparticular register or RAM locations within this chip.

Referring to a portion of FIG. 28D, a schematic diagram of the speed andthrottle input circuits 3210 are shown. These circuits are designated as3212, 3214 and 3218. The speed input signals are labeled "N_(e) /Turbo","N_(e) ", "N_(o) " and "N_(t) ". The throttle input signals are labeled"THD-GND" and "THR".

The N_(e) /Turbo and N_(e) signals are used in an application involvinga turbo equipped engine, which provides a dual pick-up in thedistributor of the engine. In this situation, both the NE and NE/Turbosignals are used to indicate engine speed. However, while these signalsprovide the same engine speed data, these signals are out of phase witheach other. In this regard, it should be noted that in distributorshaving a single engine speed pick-up, only the N_(e) signal would beused by the transmission controller 3010. FIG. 28D shows that the inputinterface circuit for the N_(e) /Turbo signal comprises a low passfilter 3212, which includes resistor R91 and capacitors C90 and C32. Thefiltered NE/Turbo signal is then directed to the "PB2" port of theinterface 3252 (chip Z135). A similar filter network 3214 is alsoprovided for the engine speed signal "N_(e) ". However, an invertingamplifier Z15 is also included as a buffer to provide the fast rise andfall times required by the microcomputer 3251 (chip Z138), as well asnoise immunity.

The "N_(o) " input signal represents the output speed of thetransmission, while the "N_(t) " signal represents the input or turbinespeed of the transmission. These signals are first filtered and thentransmitted to a zero crossing detector circuit which includes thecomparator Z47. Due to the sensitivity of these signals (e.g., minimumamplitude of 500 millivolts peak to peak), each of the comparators Z47is provided with a positive feedback loop for adding hysteresiscapability to these zero crossing detector circuits. For example,resistor R49 and capacitor C48 provide this hysteresis capability forthe output speed signal N_(o). It should also be noted that the filtercircuits for these two speed signals use a ground signal labeled"A/GNB". This ground signal represents a clean ground signal which isderived from the microcomputer 3251 (chip Z138) to heighten thesensitivity of these filter circuits. Once the output speed signal N_(o)is properly conditioned, it is transmitted to the "IC2" port of themicrocomputer 3251 (chip Z138). In contrast, the conditioned inputtransmission speed signal N_(t) is transmitted to the " NTI" port of thewatchdog/reset chip Z127 (shown in FIG. 28C).

The THR and TH-GND signal are used to indicate the throttle position inthe vehicle. These signals are processed through a unity gaindifferential amplifier circuit, which is generally designated by thereference numeral 3216. This differential amplifier circuit is used tosense the ground potential of the throttle position sensor, as well assense the potentiometer wiper signal of this sensor. The output of thedifferential amplifier circuit 3216 is directed to the "PE.0." port ofthe microcomputer 3251 (chip Z138). Since the throttle position signalis an analog input signal, it should be appreciated that themicrocomputer 3251 (chip Z138) includes an internal analog to digitalconverter to permit further processing of this signal in accordance withthe control methodology discussed above.

This is further illustrated in conjunction with FIG. 33 where thedissimilar grounds of the engine controller 3020 and transmissioncontroller 3010 are graphically depicted. Attention is invited also tocircuit 3216 in FIG. 28D. Dissimilar grounds can generate a variablereference to ground. This is a function of variable resistance andinductance in the vehicle and its electrical system. The variable groundreference could be a significant percentage of the span of the outputvoltage from the throttle position sensor. Therefore, without thefeature of the shared throttle position sensor circuit, two sensorswould be needed.

FIG. 28D also shows a portion of the ignition switch interface circuits3220. Specifically, FIG. 28D shows the interface circuit 3218 for theignition switch signal "J2". The interface circuit 3218 provides a lowpass filter whose output is directed to the "FJ2" port of thewatchdog/reset chip Z127.

Turning to FIG. 28E, the last of the ignition switch interface circuits3220 is shown. Specifically, an interface circuit 3222 for the crankonly ignition signal "S2" is shown. The interface circuit 3222 includesa voltage divider (R78 and R80), a low pass filter (R61 and C79), and acomparator Z47. The voltage divider is used to decrease the voltagelevel of the S2 signal, so that it does not exceed the maximum inputvoltage of the comparator. The output of the comparator Z47 is connectedto the "FS2*" port of the watchdog/reset chip Z127. The S2 ignitionsignal is used to hold the microcomputer 3251 (chip Z138) in a resetmode during the cranking of the engine. This provision is implementedfor purposes of accuracy, since it is possible that the battery voltagein the vehicle could dip down during the cranking of the engine.

CIRCUIT FOR DETERMINING THE CRANK POSITION OF AN IGNITION SWITCH BYSENSING THE VOLTAGE ACROSS THE STARTER RELAY COIL AND HOLDING ANELECTRONIC DEVICE IN A RESET CONDITION IN RESPONSE THERETO

FIG. 28E also illustrates the PRNODDL interface circuits 3230.Specifically, FIG. 28E shows the circuits used to interface the neutralstart signals "NS1" and "NS2", as well as the circuits used to interfacethe reverse light signals "RL1" and "RL2". Each of these signals aredigital signals which will generally be at a zero or battery voltagepotential. Accordingly, each of the interface circuits for the signalsinclude a pair of voltage dividing resistors (in addition to a filter)for getting the battery voltage level down to a 5 volt potential. Inthis regard, it should be noted that each of these input signals arecoupled to the ignition switch signal "J2" through suitable pull-upresistors (e.g., R82 and R83) to ensure that these signals will providebattery voltage potential when their corresponding switches are open.

While the conditioned NS1 signal is transmitted to the "PE5" port of themicrocomputer 3251 (chip Z138), this signal also provides a gatingsignal to the transistor Q93. The transistor Q93 is used to disable theS2 signal from causing a reset of the microcomputer 3251 (chip Z138). Inother words, when the contact switch NS1 is open, the NS1 signal will beHIGH, thereby causing the transistor Q93 to conduct and pull down theinput voltage to the comparator Z47. This provision is to ensure thatthe S2 signal does not cause a reset unless the transmission 100 iseither in neutral or in park. This is also graphically depicted in FIG.34 and its accompanying chart of the states of the contacts, devices andoutputs.

Referring to FIG. 28F, a schematic diagram of the regulator circuit 3290and the relay driver circuit 3270 is shown. Additionally, FIG. 28F showstwo capacitors (C228-C233) which are used to tie the grounding potentialof the circuit board for the transmission controller 3010 to thealuminum case which surrounds the circuit board. This optional featuremay be used to provide additional RF or electromagnetic compatibilityfor the transmission controller circuitry.

DUAL REGULATOR

The regulator circuit 3290 shown in FIG. 28F generally comprises a dual5 volt regulator chip Z215 which receives a voltage input signal fromthe vehicle battery and a command signal from the watchdog/reset chipZ127. This command signal, labeled "PSENA*", is used to enable or switchon and off the "VO2" output of the regulator chip under MCU command whenignition is off. The VO2 output of this chip provides the "SW/5 V"supply signal discussed above. This provision of a switchable 5 voltsupply is particularly advantageous in a vehicle application, as itpermits a substantial portion of the peripheral circuitry (or circuitrywith a low priority) connected to the micro core 3250 to be shut downwhen the vehicle ignition is off thus reducing current draw on thebattery. This can also be used under conditions requiring an orderlyshutdown for purposes of storing last-sensed data etc. A continuousvoltage output can be provided to high priority circuits such as amemory chip or a MCU. It can also be used to keep high priority circuitsenergized in a "KEY-OFF" situation, if desired, to allow for example thecontrol of gear selection/display while the engine is off.

SHUTDOWN RELAY DRIVER

The shutdown relay driver circuit 3270 includes a self protecting, highside switch chip Z219 which is responsive to a "RLYCNT" control signalfrom the watchdog/reset chip Z127. Specifically, the relay controlsignal will cause the battery voltage to be transmitted to the "VOUT"port of the switch chip Z219. This voltage output from the chip Z219 isreferred to as the "RELAY/PWR" signal, as it provides the powernecessary to operate the shut down relay 3272 shown in FIG. 30. The shutdown relay 3272 is used to cut power off to the solenoid driver circuits3280 to thereby achieve a "LIMP-IN" mode previously described.Specifically, when the shut down relay 3272 is closed, the "SW/BATT"signal shown in FIG. 28F will be transmitted to the solenoid drivercircuits 3280. However, before this SW/BATT signal is transmitted to thesolenoid driver circuits 3280 it is processed through conditioningcircuit 3274. The conditioning circuit 3274 includes a diode "D224"which is used to clamp the back EMF of the solenoid coils when the shutdown relay 3272 is open. The conditioning circuit 3274 also includes apull down resistor R225 to ensure that the line is pulled to grounddespite the states of the solenoid driver circuitry. A capacitor C223 isalso provided to suppress any line inductive energy spikes that mightoccur in response to the switching of the transmission solenoids.

THE USE OF DIODES IN AN INPUT CIRCUIT TO TAKE ADVANTAGE OF AN ACTIVEPULL-DOWN NETWORK PROVIDED IN A DUAL REGULATOR

It should be noted that both the "RELAY/PWR" and "SW/BATT" signalsprovide input signals to the conditioning circuit block 3310. In thepresent embodiment, the conditioning circuit block 3310 employs thickfilm packaging technology to effectively create a single compact chipfor the circuits contained in this block. The conditioning circuit block3310 is comprised of four identical conditioning circuits 3320-3350.Each of these conditioning circuits include an RC filter (R300 and C200)and a pair of voltage dividing resistors (R301 and R302). Since theSW/BATT and RELAY/PWR signals are at the battery voltage potential, thevoltage dividing resistors cut this voltage level down to the 5 voltlogic level used in the micro core 3250. This is also furtherillustrated in FIG. 31 which shows this concept in a simpler form.

It is also important to note that each of the conditioning circuits3320-3350 include a diode "D300" which connects the input signal of eachof these circuits to the SW/5 V supply line. This is a particularlyadvantageous feature of the present invention, because the regulatorchip Z215 will actively pull the SW/5 V signal level down to groundduring an over voltage condition (e.g., where the battery voltageexceeds 30 volts). Accordingly, the diode D300 will clamp the batteryvoltage level input signals to the conditioning circuits 3320-3350 downto ground during such an over voltage condition. This will preventexcessive input signals from being transmitted to the micro corecircuits 3250 via ESD protection diodes. In this regard, for example,the RELAY/PWR signal is transmitted to the "PB.0." port of the interfacecircuit Z135 of the micro core 3250 through the conditioning circuit3330. This feedback provision will enable the microcomputer 3251 (chipZ138) to confirm the status of the relay driver circuit 3270 and is alsoused while testing the watchdog reset.

OPEN LOOP CONTROL OF AND SPIKE MONITOR FOR SOLENOID COIL DRIVERS

Referring to FIG. 28G, a schematic diagram of the solenoid drivercircuits 3280 is shown. The solenoid driver circuits 3280 comprise anindividual driver circuit for each of the four solenoid-actuated valves630, 632, 634 and 636 contained in the transmission namely, drivercircuits 3282-3288. Each of these driver circuits is provided with twoinput signals, one of which is derived from the interface 3252 (chipZ135) and the other of which is derived from the microcomputer 3251(chip Z138). For example, in the driver circuit 3282, an enablementcommand signal is transmitted from "PC6" port of the interface 3252(chip Z135), and a current control signal is transmitted from the "OC2"port of the microcomputer 3251 (chip Z138). The OC2 signal is derivedfrom an internal timer of the microcomputer 3251 (chip Z138).Specifically, the OC2 control signal generated by MCU timer functionsprovides a series of pulses which have an appropriate duty cycle forcausing a pulse width modulation of the current to the solenoid coil,such as the underdrive (UD) coil, in addition a "pull in" pulse is MCUtimer generated when the solenoid coil is first turned on.

When the microcomputer 3251 (chip Z138) causes the interface 3252 (chipZ135) to latch its "PC6" port into a HIGH state, the driver circuit 3282will be enabled through the gating on of transistors Q177 and Q169. Thegating on or HIGH pulse of the OC2 signal will permit the current in theUD solenoid coil to charge up through the transistor Q179. Then, whenthe pulse of the OC2 signal is turned off, current through the UDsolenoid coil will circulate in the path created by the diode D168 andtransistor Q169. The result will be an efficient slow decay of thecurrent through the UD solenoid coil. At this point, it should be notedthat the junction between the Darlington pair transistor Q169 and theMOSFET resistor Q179 will be at a potential above the potential of theSW/BATT supply signal.

Subsequently, when the microcomputer chip Z138 causes the "PC6" port ofthe interface 3252 (chip Z135) to switch to a LOW state, the transistorQ177 will switch off and cause a rapid decay of current through the UDsolenoid coil. When the gate signal is removed from the transistor Q177,it should be noted that the Darlington pair transistor Q169 will alsoturn off. This rapid decay of current will also cause the voltage on theconductor 3289 to rise above the SW/BATT potential. At some point (e.g.,25 volts), this rising potential will cause the Darlington pairtransistor Q169 to turn on again to limit the spike of this risingvoltage potential. However, it is important to note that the voltagepotential on conductor 3289 is transmitted through the diode "D174" tothe zener diode "D173". At a predetermined potential (e.g., 24 volts),the zener diode D173 will breakdown and cause current to flow throughthe transistor Q168 to the "PB3" port of the interface 3252 (chip Z135).

This spike monitor circuitry is an important aspect of the presentinvention, as it allows the microcomputer 3251 (chip Z135) to determinewhether the solenoid coil is in a shorted or open condition. In otherwords, the spike monitor circuitry of the solenoid driver circuits 3280will tell the microcomputer 3251 (chip Z138) that the solenoid coil hasindeed turned off. In this regard, it should be noted that the SW/BATTsignal continually keeps the transistor Q168 in a conducting condition,so that the current from conductor 3289 will pass directly through itsemitter and collector junctions for transmission to the "PB3" port ofthe interface 3252 (chip Z135).

It should be appreciated that the diode "D173" is connected to each ofthe driver circuits 3282-3288 through appropriate diodes (e.g., D175 andD202), so that the microcomputer 3251 (chip Z138) will be able to detectthe presence of a voltage spike from each of these driver circuits.While each of the driver circuits 3282 are substantially identical, theconnections employed in the driver circuit 3282 will be brieflydescribed.

The OC2 port of the microcomputer 3251 (chip Z138) is connected to thegate of the MOSFET transistor Q179 through the resistor R161. The sourceof the transistor Q179 is connected to ground, while the drain of thistransistor is connected to one end of the UD solenoid coil. The otherend of the UD solenoid coil is connected to the junction between theSW/BATT potential and the diode pair D168. The common emitter junctionof the Darlington pair transistor Q169 is connected across the reversebias diode in the diode pair D168, while the collector junction of thetransistor is connected to the drain of the MOSFET transistor Q179. Acapacitor C248 is coupled across the collector and base junctions of theDarlington pair transistor Q169 for stability, while a resistor R298 isconnected across the base and emitter junction of this transistor toprovide sufficient current for spike monitor operation. The base of thetransistor Q169 is also connected to the collector junction of thetransistor Q177 through the resistor R178. The base of the transistorQ177 is coupled to the "PC6" port of the interface circuit Z135 throughthe transistor R176. The emitter junction of the transistor Q177 isconnected to ground. The conductor 3289 is connected to the collectorjunction of the transistor Q177, and is coupled to the diode D174through one of the diodes labeled "D175".

FIG. 35 is an illustration of closed loop and open loop control ofsolenoid coil drivers showing basic differences between the circuits andbasic similarities between the voltage outputs. An electronic drivercircuit for the open loop control of the energization of a solenoidcoil, forming part of an electromagnetic solenoid actuator valve, inresponse to a control pulse produced by a control circuit and where thepredetermined schedules are a function of the inductance and resistanceof the coil, the desired peak output voltage from the coil and thedesired average holding current through the coil.

The principals of the injector driver circuit are also described inco-assigned U.S. Pat. No. 4,631,628, issued on December 23, 1986, whichis expressly hereby incorporated by reference.

Referring to FIG. 28H, a schematic diagram of the pressure switchinterface circuits 3240 is shown. The pressure switch interface circuits3240 are generally embodied in a conditioning circuit block 3242 whichis identical to the conditioning circuit block 3310 in the presentembodiment. Thus for example, the conditioning circuit block 3242includes a conditioning circuit 3244 for the "KDPR-SW" pressure switchsignal. It should also be noted that the conditioning circuit block 3242includes a conditioning circuit 3246 which has an input signal labeled"CK/TRANS/LTG". This input signal is generated in the diagnostic alertcircuit 3500 shown in FIG. 28I.

Referring to FIG. 28I, the diagnostic alert circuit 3500 is shown to beprovided with an input signal labeled "FSW/BATT", which represents thefiltered battery voltage level produced at the output of theconditioning circuit 3320 shown in FIG. 28H. As discussed previously,the SW/BATT signal indicates that the battery voltage is being suppliedto the solenoid driver circuits 3280. The conditioning circuit 3320 isused to drop this voltage level down to a usable 5 volt logic levelwhich is fed back to the "PC7" port of the interface 3252 (chip Z135)through the diode "D162" of the diagnostic alert circuit 3500.

The FSW/BATT signal is transmitted through an inverting amplifier Z15which is used to gate the MOSFET transistor Q165. The transistor Q165produces the CK/TRANS/LTG signal which may be used to alert the operatorthat power has been cutoff from the transmission solenoid-actuatedvalves 630, 632, 634 and 636, such as through a light on a diagnosticpanel in the passenger compartment. In an application involving the useof the diagnostic alert circuit 3500, the conditioning circuit 3246shown in FIG. 28H will provide a feedback signal to the "PA1" port ofthe interface 3252 (chip Z135) to confirm that the diagnostic panel hasbeen provided with the appropriate signal.

FIG. 28I also shows an additional communication circuit 3400 whichprovides a direct serial transmission link from the transmissioncontroller 3010 to the engine controller 3020. Such a separatetransmission channel may be employed when it is desired to send highpriority or rapid signals to the engine controller 3020. For example, insome applications it may desirable for the transmission controller 3010to advise the engine controller 3020 that a gearshift is about to takeplace. In such a situation, the microcomputer 3251 (chip Z138) wouldcause an appropriate signal to be placed on the "PB7" port of theinterface 3252 (chip Z135) to gate on the transistor Q243. The gating onof the transistor Q243 will generate the "TRDLINK" signal through thefilter network comprised of resistor 245 and capacitors 244 and 246.

Referring again to FIG. 28H, the test mode circuit 3300 is shown toinclude the conditioning circuit 3350. When a testing mode for thetransmission controller 3010 is desired, the "test" input signal will beHIGH, thereby causing a LOW "modea/lir" signal to be transmitted to themicrocomputer chip Z138. This signal will cause the microcomputer chipZ138 to initiate the test mode sequence discussed above.

Referring to FIG. 29, a block diagram of the interface chip Z135 isshown. The pin designations shown in this figure (e.g., "PC0-PC7")generally correspond to the pin designations shown for the interface3252 (chip Z135) in FIG. 28B. There is one exception to thiscorrespondence. In FIG. 28B, the pins for Port-A are designated"AD0-AD7"; whereas, in FIG. 29, these pins are designated "D0-D7".

In addition to Port-A, the interface chip Z135 also includes two otherports, namely Port-B (i.e. pins PB0-PB7) and Port-C (i.e. pins PC0-PC7).Pins PB0-PB3 of Port-B are connected to the edge detect input circuits3600. The edge detect circuits 3600 provide a way to capture theoccurrence of an event, such as the turning off of a coil of asolenoid-actuated valve, at a time when the microcomputer 3252 (chipZ138) might otherwise be occupied. Thus, for example, pin PB3 of theinterface 3252 (chip Z135) is connected to the spike monitor circuitryof the solenoid driver circuits 3280 in order to transmit a signalindicative of the turning off of a coil of a solenoid-actuated valve tothe microcomputer 3251 (chip Z138) through interface 3252 (chip Z135).When such a signal is received, the interface 3252 (chip Z135) cangenerate an interrupt signal IRQ* which will inform the microcomputer3251 (chip Z138) that event information has been received for furtherprocessing.

The interface 3252 (chip Z138) also includes a plurality of countdowntimers 3602, which are responsive to the "E" clock signal of themicrocomputer, through the E-clock prescaler circuit 3604. The outputfrom these timers may be transmitted to pins PB4-PB7 through the timeroutput circuitry 3606, in the event that the timer features of theinterface chip are desired to be employed. Otherwise, the pins PB4-PB7may be used as general purpose output pins.

While Port-C of the interface 3252 (chip Z135) could be used as a loworder address port, the mode select signal "MS" is used in the preferredembodiment to configure this port as an output port. In thisconfiguration, the address strobe signal "AS" from the microcomputerchip Z138 is used to command the address latch 3608 to capture low orderaddress information at AD0-AD7 of the interface 3252 (chip Z135).

The interface 3252 (chip Z135) also includes a random access memorycircuit 3610, a plurality of internal registers 3612 and a decoder logiccircuit 3614. Particular locations in the RAM 3610 and particularinternal registers 3612 may be accessed through the decoder logiccircuit 3614, which is responsive to the address signal pins "A13-A15"in addition to the latched low order address A₀ -A₇. The internalregisters 3612 are used to provide access and control of the variousports and counters for the interface 3252 (chip Z135).

Referring to FIG. 30, a block/schematic diagram of the watchdog/resetcircuit Z127 is shown in association with some of the circuits connectedto the watchdog/reset circuit Z127. The first function of thewatchdog/reset or "WD" circuit is to monitor the operation of themicrocomputer 3251 (chip Z138) by requiring the MCU to periodicallytransmit a signal to the WD circuit. This signal is designated "WDG" inboth FIGS. 28C and 30. If the WD circuit does not receive the WDG signalwithin a predetermined time window, then the WD circuit will know thatthe MCU may not be functioning as desired. However, before the WDcircuit will react to this situation, it will wait a predeterminedamount of delay time to see if proper functioning of the MCU will bequickly restored. If the WDG signal is not received by the end of thedelay period, then the WD circuit will transmit a "RLYCNT" signal to therelay driver circuit Z219 which will cause the shutdown relay 3272 toremove electrical power from the solenoid driver circuit 3280.

In this regard, FIG. 30 shows that the WD circuit includes a windowdetector circuit 3700 which receives the WDG signal. The window detectorcircuit 3700 includes an up counter which is reset by the WDG signal,and a pair of comparators which determine whether or not the WDG hasbeen received within the predetermined time window (e.g., 14 ms.). Ifthe WDG signal is received too early or too late, or not received atall, then the Q output of the window detector will switch to a LOWdigital state. This will in turn drive the output of AND gate 3702 LOW.

The output of the AND gate 3702 is connected to a fault delay circuit3704 and to a conductor 3706. The fault delay circuit 3704 will give theMCU a predetermined time period (e.g. 64-512 ms.) to transmit the WDsignal. This time period may be altered between four different valuesdepending upon the particular voltage or ground connections for theinput signals "DLYA" and "DLYB". In the meantime, the conductor 3706will transmit the "WDFLT" feedback signal, and provide a way ofseparately testing the operation of the window detector 3700 and thefault delay circuit 3704 within the WD circuit. The conductor 3706 isconnected to an input of the AND gate 3702 through the resistor 3708 andconductor 3710. To test the fault delay circuit 3704, the MCU willtransmit the "DLY/MON" signal, which will drive the AND gate 3704 LOW inorder to simulate the absence of the WD signal from the window detectorcircuit 3700.

If the WD signal is not received within the time period controlled bythe fault delay circuit 3704, then the AND gate 3712 will switch states,and cause the relay driver circuit Z219 to cut off power through thelogic connections provided by OR gate 3714 and AND gate 3716. The ANDgate 3712 also receives a "Latchdown" signal from the relay drivercircuit, which will prevent the AND gate 3712 from switching statesagain until the reset start-up sequence is initiated, even if the MCUtransmits a proper WDG signal in the intervening time period. In otherwords, once the WD circuit Z127 causes the relay driver circuit Z219 toremove electrical power from the solenoid driver circuit 3280, the resetstart-up sequence must be initiated before power will be restored to thesolenoid driver circuit.

The WD circuit is also responsive to a master kill signal "MK" from theMCU for removing power from the solenoid driver circuit 3280. In otherwords, when the MCU determines that power should be removed for whateverreason, then the MK signal will be transmitted to the relay drivercircuit through the AND gate 3716.

Another function of the WD circuit Z127 is to control the reset start-upsequence which will occur, for example, when electrical power is firstapplied to the transmission controller 3010. When power is firstapplied, this sequence will be initiated by the master reset signal"MRST", which is derived from an RC delay off the VDD power supply.

The reset start-up sequence may also be initiated from a filtered doorentry signal "FENTRY". This optional feature could be provided when itis desired, for example, to have the vehicle electrically display thecurrent PRNODDL transmission mode in response to the opening of thevehicle door, prior to the time that the key is inserted into thevehicle ignition. The reset start-up sequence may also be initiated froman actuation of the ignition key, via the ignition signal "FJ2".

The WD circuit includes a pair of one shot multivibrators 3718-3720,which will generate a single or one shot pulse output whenever theFENTRY or FJ2 signals are received. The output from one shot 3718 iscombined with the FJ2 signal at the AND gate 3722, while the output ofthe one shot 3720 is fed directly to the NOR gate 3724. The output fromthe NOR gate 3724 is connected to the reset input to the counter 3726.Accordingly, it should be appreciated that the NOR gate 3724 serves tocombine all those inputs which can cause a reset condition to begenerated.

The counter 3726 will generate the reset signal "MPURST", which will betransmitted to the MCU through the buffer 3728. The counter 3726 willalso generate a false OK signal on conductor 3730, which is necessary tooverride or reverse the Latchdown signal. Thus, in the situation wherethe Latchdown signal has been generated, the momentary false OK signalwill allow re-enablement of the relay driver circuit Z219 through ORgate 3714 and AND gate 3716. This re-enablement will, in turn, overridethe state of the Latchdown signal, and permit electrical power to thesolenoid driver circuit 3280 to be applied.

While the above described reset start-up sequence will cause only amomentary MPURST signal to be transmitted to the MCU, the WD circuitalso includes a provision for maintaining the presence of this resetsignal in response to predetermined regulator conditions. In thisregard, it should be appreciated that the continued presence of thereset signal will disable the operation of the MCU, until properoperation of the regulator is restored and the reset signal is removed(i.e. the digital state of this signal is changed).

THE UTILIZATION OF A RESET OUTPUT OF A VOLTAGE REGULATOR AS A SYSTEMLOW-VOLTAGE INHIBIT

As shown in FIG. 30, the regulator circuit Z215 will generate a powersupply reset signal "PSRST", which will be transmitted to the NOR gate3724 through the AND gate 3730. This power supply reset signal will begenerated whenever the input voltage to the regulator is too low or toohigh, or when the regulator is being overloaded.

This feature provides for increased system integrity by holding the MCU3251 and the transmission controller 3010 in a predetermined RESET stateunder certain conditions including those shown in conjunction with FIG.32.

Here a reset output is generated on the powering down of a switch. Inother words, the "peripherals" are reset on power-up.

An "additional" RESET mode is provided by the regulator (as shown inFIG. 32) that must be gated out through the watchdog/reset circuit shownin FIG. 30; it also responds to the switching off of the second voltageregulator signal.

Another function of the WD circuit Z127 is to divide the turbine speedsignal "N_(t) " down so as to reduce the interrupt burden on the MCU.Accordingly, the WD circuit includes a programmable frequency divider3732 which receives the turbine speed signal N_(t). The divide controlsignals "DIVA" and "DIVB" from the MCU are used to determine one of fourdifferent divide ratios to be employed by the divider 3732.

It should also be noted that the WD circuit includes a block 3734 whichis labeled "prescaler/system clocks". This block comprises a timer witha prescaler which is used to provide both reset and start-up times, aswell as the fault delay and window detector clock signals employed inthe WD circuit.

The present invention has been described in an illustrative manner. Itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations are possible in light ofthe above teachings. Therefore, the subject invention may be practicedotherwise than as specifically described.

What is claimed is:
 1. A vehicle transmission park lock mechanism foranchoring a transmission power output member to a transmission housingcomprising:a gear member carried by and rotatable with a transmissionpower output member and having external teeth; a parking pawl membermounted to a transmission housing for pivotal movement about a firstaxis, said parking pawl member having a male portion adapted to engage arecess between adjacent teeth of said gear member in a first position;spring biasing means biasing said parking pawl member away from saidgear member to disengage the recess between adjacent teeth of said gearmember in a second position; an actuator assembly for pivotally movingsaid parking pawl member between said first and second positions; andguide bracket means mounted to the transmission housing and adapted toreceive said parking pawl member for operatively cooperating with saidactuator assembly to pivotally move said parking pawl member betweensaid first and second positions; a plate member mounted for pivotalmovement on a second axis orthoganal to said first axis for actuatingsaid actuator assembly; said actuator assembly comprising a rod member,a U-shaped carrier formed with parallel side flanges fixed at one end ofsaid rod member, the other end of said rod member being pivotallyconnected to said plate member, a pair of parallel pins extendingbetween and fixed to said side flanges, said carrier having a pair ofcam rollers each formed with a central bore, said bore receiving acorresponding one of said pins therethrough, the diameter of said borebeing greater than the diameter of said pin such that each said rolleris free for predetermined limited transverse movement relative to itsassociated pin so as to rollingly engage the other roller; said guidebracket means comprising a guide bracket having a pair of side wallsinterconnected by a bracket wall, said side walls located in parallelplanes; and said bracket wall having a main portion and an offsetportion interconnected by an oblique portion, said carrier adapted to bemoved between said side walls by the actuation of said rod member assaid plate member is rotated such that one of said rollers successivelycontacts said main portion, said oblique portion, and said offsetportion of said bracket wall to move said parking pawl member.
 2. Avehicle transmission park lock mechanism for anchoring a rotatablemember of a gear assembly of a vehicle transmission to a transmissionhousing of the vehicle transmission, comprising:a parking pawl membermounted on a housing pivot pin for pivotal movement about a first axis,said parking pawl member having a male portion adapted to engage arecess between adjacent teeth of the rotatable member in a firstposition; spring biasing means biasing said parking pawl member awayfrom said rotatable member to disengage the recess between adjacentteeth in a second position, said parking pawl member having a camsurface thereon; a plate member mounted for pivotal movement on a secondaxis orthoganal to said first axis; an actuator assembly for pivotallymoving said parking pawl member between said first and second positions;said actuator assembly comprising a rod member, a U-shaped carrierformed with parallel side flanges fixed at one end of said rod memberand its opposite end pivotally connected to said plate member, a pair ofparallel pins extending between and fixed to said side flanges, saidcarrier having a pair of cam rollers each formed with a central bore,said bore receiving a corresponding one of said pins therethrough, thediameter of said bore being greater than the diameter of said pin suchthat each of said cam rollers is free for predetermined limitedtransverse movement relative to its associated pin so as to rollinglyengage the other roller; a channel-shaped guide bracket mounted on thehousing pivot pin and having a pair of spaced side walls interconnectedby a bracket wall, said side walls located in parallel planes; saidbracket wall having a main portion and an offset portion interconnectedby an oblique portion, said carrier being adapted to be moved betweensaid side walls of said bracket by the reciprocal travel of said rodmember when said plate member is rotated, said one roller contacts saidcam surface of said parking pawl member and said other rollersuccessively contacts said main portion, said oblique portion, and saidoffset portion of said bracket wall; whereby one of said cam rollerscontacts said offset portion and the other of said cam rollers contactssaid cam surface causing said parking pawl member to be pivoted towardthe rotatable member against said spring bias such that said parkingpawl member lockingly engages in one of the rotatable member recesses.